Serial Numbers
Contents
(Scroll down or click on links)
Serial Number Patterns
Decoding Serial Numbers
Serial Numbers from 1957 to 1960
Serial Numbers from 1961 to 1980
7 Digit Numbers  Correlation to Model Release and End Dates
The Yashica Spares System Theory  the Impact on Serial Numbers
Do These Patterns and Date Codes Exist for Other Format Yashica Models?
Serial Numbers Found  All TLR Models
Location of Body Serial Numbers
Serial Number Patterns
Originally, body serial numbers were generally consecutive within a model's production, although sometimes the numbers jumped, or increased digits, at some significant point. The first exception is the first model, the Pigeonflex! Following the first few examples in my database, the body serial numbers dropped some 40,000. The Yashicaflex ASII is another exception with a short series in the 30xxx range, then from 81xxx to 83xxx followed by a new series from 19xxx to 23xxx. The MolfoReflex has three unrelated serial number ranges. Serial numbers were not consecutive model to model, usually. Two possible exceptions are from Yashima Flex to Yashica Flex B (there may have been a minor jump by about 2,000 or so) and from Yashica Mat124 to Yashica Mat124G where the numbers appear to continue on. However, in the latter case, production switched from one model to the other and the appearance of continuity is given by the numbers based on a date code (see below).
As the “Yashica” models came into play, things became interesting with odd sequences, some earlier numbers having more digits than later ones. The numbers seemed to be most confusing in the 1957 to 1960 period after which cameras still in production adopted serial numbers with prefixes and settled into a more logical progression again. The affected models are the Yashica A, B, D and 635 and YashicaMat at, or towards, the beginning of their production, the Yashicaflex A (new model) and B (new model), Yashica C and LM at the end of their production and the second two thirds of Yashica 44 and first half of 44A and 44LM production. Yashica also opened their New York office in 1957  is the new numbering system somehow linked, or a complete coincidence?
As an example, the Yashica A begins with 5 digit numbers, then changes to 6 digit numbers beginning with 79, then changes to 8 digit numbers starting with 5710, followed by 7 digit numbers beginning with 584. Then there are 8 digit numbers beginning with 3810 followed by 7 digit numbers beginning with 391 and then 8 digit again with 3910. These are followed by 6 digit numbers beginning with 61. And then there is the 9 digit 116110451. Similar patterns are found with the other models in this period and usually, the first few digits are the same across the models.
The final block of Yashica A numbers have an “A” prefix. However, the second (from the left) digit of the “A” numbers rarely is higher than “0” and never more than “1” so that there will be for example A 20xxxxx and A 21xxxxx but never A 22xxxxx, the next number being in the A 30xxxxx range. This happens with all the alpha prefixed numbers for all models and also occurs with the unprefixed 7 digit numbers of the Yashica Mat124 and Yashica Mat124G. Finally, the solution has hit me in the face  see below:
The Yashica 635 changed its alpha prefix from ST to SX. When the numbers appeared to run out, the Yashica Mat124G changed from a 7 digit series, with the “0” and “1” pattern noted above, to a new 6 digit series with no “0” and “1” pattern.
Lens numbers began logically but there are some other oddities too. Early in the piece, the Yashica Flex B seems to have started with six digit numbers and then changed to a new series with 5 digits. Some later cameras seem to have blocks of numbers issued almost randomly. Even if there is consistency, it is not unusual for a later camera to have slightly earlier lens numbers than the cameras immediately before it. Generally, the ranges for taking lenses and viewing lenses are the same and often, particularly with earlier cameras the numbers are in close proximity.
To me, there are three issues which contribute to the difficulty with serial numbers. The most obvious problem is that for a time, Yashica used a system that made sense to it but until now, we didn't have the key to decipher  we could get a picture of the correct order from trim and detail changes but not understand the reasoning. The second problem is that serial numbers were prestamped on peripheral parts that were delivered separately to the production line and presumably there was more than one line. It's obvious how body numbers, taking lens and viewing lens numbers can easily get out of sequence with each other, if allowed to (not generally the case with bodies), which brings us to the third issue  I don't think keeping lens numbers in sequence was a high priority, certainly at certain times of production. In the end, the numbers disappeared from first, the viewing lenses and then the taking lenses.
Decoding Serial Numbers
As noted above, the early cameras used consecutive number sequences, usually unique but not always.
I believe that serial numbers from September 1957 to February 1980 contain a date code and that I have deciphered that, bit obvious with hindsight really. However, even if I am 100% wrong, by strange coincidence or otherwise, my system will allow you to date a camera from that period to within 12 months of what my database, model release dates and acrosstheboard trim changes predict.
The key is that with alpha prefixed and late 7 digit serial numbers, not only is the second digit from the left never higher than “1”, the second and third digit together are always in the range “01” to “12”. How simple is that? The step to seeing year and sequence numbers is not great, I have been numbering my digital files since 2005 with year, month and 4 digit sequence codes. With the earlier numbers, the pattern is similar but mostly, the month numbers are “1” to “12” so that at “9”, numbers are 7 digit but at “10”, they become 8 digit. There are some variations with the pre1961 numbers and the year codes are “interesting”  that is where I believe the guess work is.
This is how I believe the numbers from 1957 to 1980 operate but you will have to read the following sections to understand the logic and how to apply that knowledge.
Model Identifier  Year  Month  Monthly Count from Zero 

Nothing, 2 digits or alpha sequence 
1 or 2 digits 
1 or 2 digits 
4 digits 
Serial Numbers from 1957 to 1960
The September 1957 to December 1960 models used 6 digits, 8, 7, 8, 7, 8, 6 and some briefly (the Yashica 44LM not so briefly), 9 digits. Sometimes the combinations were slightly different. At this stage, I think that I understand the patterns and month codes but for the year codes, I will need to make some educated guesses. Two assumptions I will be making are that the last 4 digits on the right are a production sequence number, probably starting at zero each month and that all the preceding digits to the left are year and month codes, except in one case (the last numbers in the series) where there is also a model code.
I am going to start with the last numbers first because one, they are easier and two, they are more likely to be related to the following prefix series which seem straightforward in comparison. Only one Yashica A (serial number 11611xxxx), one Yashica 635 (serial number 13611xxxx), two YashicaMats (serial numbers 14610xxxx), two Yashica MatLMs (serial numbers 15609xxxx and 15611xxxx ) and nineteen Yashica 44LM (serial numbers 16609xxxx to 16611xxxx) examples have 9 digit serial numbers. My guess is that the first 2 digits from the left indicate model, the 3rd digit, the “6” indicates the year, in each case 1960 and the 4th and 5th digits indicate the month from 09 to 11 in the examples found. This was a short lived interim system. Effectively, in 1961, an alpha code replaced the 2 digit model code. In summary:
11 = Yashica A
12 = ?
13 = Yashica 635
14 = YashicaMat
15 = Yashica MatLM
16 = 44LM
That leaves the Yashica B, D and 44A without any examples so far. My guess is that “12” was probably allocated to the Yashica D and the Yashica B and the Yashica 44A missed out. The Yashica B was a low volume model, possibly offered in limited markets and was likely made in limited batches. 44 model production seemed to be very heavily focused on the 44LM in this period.
Before these examples, every model in production at the time had a bunch of similar 6 digit numbers beginning with 6. These ranged from 61xxxx to 69xxxx. There doesn't appear to be a model code. I interpret these numbers to be “6” for 1960 and “1” to “9” to be the months January to September.
That takes care of the whole of 1960. Now let's rewind to the beginning of this period, 1957. Until about September of that year, each model had a straightforward and mostly unique consecutive number series with the odd jump here and there. Then coincidentally, all models in production received a new 6 digit numbering system beginning with “79” (perhaps not the rare Japanese market Yashicaflex A which had just been released in August). The first digit could represent 1957 and the digit “9” could represent September which was pretty close to the start point.
This applied to the Yashica A, C, LM, YashicaMat and Yashicaflex B. As new models were introduced, they picked up on the apparent date patterns that followed except for the Yashica 635 and Yashica 44 both of which were claimed to be introduced in June 1958 and seem to initially start with their own discrete 5 digit consecutive series before switching to what looks like a 1958 date code.
The Yashica LM is also found with 7 digit serial numbers from 710xxxx to 711xxxx which I believe represent the months of October and November 1957. It is possible that other models also exhibit the same pattern but the evidence suggests not. There was also a small anomaly with the YashicaMat. September seems to start off with 79xxxx numbers but later in the month, a new series starts! These 579xxxx numbers have the later style of a new range of numbers with 8 digits ranging from 5710xxxx to 5712xxxx (from 5711xxxx for the Yashica LM). My guess is that the year is still 1957 and the months are October to December.
Note that the Yashicaflex B (new model) adopted the new “79” 7 digit numbering system initially but the next range of numbers have different numerical prefixes to other models and whilst the schema look similar, I can't directly relate them to dates. By this stage, the prefixes are shared with the Yashicaflex A (new model). Both are domestic Japanese models and the last of the Yashicaflexes and could have been given their own series for some reason. The two Yashicaflexes have numbers ranging from 3210xxxx to 3212xxxx. The numbers seem to imply October to December and seem to align with the 5710xxxx to 5712xxxx numbers of other models. Perhaps “32” is code for “57”, i.e. 1957? That is what I think.
What I assume are 1958 numbers are back down to 7 digits and range from 581xxxx to 589xxxx with “58” equating to 1958 and “1” to “9” representing January to September. Seemingly logical. The two Yashicaflexes have similar pattern numbers but the first two digits are “33” so maybe that is code for 1958. They go up to “338xxxx”, I assume August.
The next 15 months requires a real leap of faith to believe that there is a date code. The 1958 numbers appear to have made it to September (“58” for Yashicas and “33” for Yashicaflexes). However, also beginning in September 1958, all models moved to “38” for 1958. So September 1958 numbers can be 7 digit numbers 589xxxx for Yashicas, 339xxxx for Yashicaflexes or 389xxxx for either variety. The new 7 digit numbers only appeared for part of one month and so far I have only found YashicaMat, Yashicaflex B and Yashica 44 examples. Why “3” instead of “5”? My only guess is that Yashica was trying to get a little tricky with disguising its production details, something perhaps started with the home market Yashicaflexes. Logically and in a similar pattern to 1957, the October to December numbers appear to be 8 digit numbers 3810xxxx to 3812xxxx.
1959 serial numbers seem to start with a familiar 7 digit pattern, 391xxxx to 399xxxx which I interpret to mean 1959, January to September. Then come the familiar 8 digit numbers but only for October, 3910xxxx to 3910xxxx. October also seems to bring a change to a new “4” prefix instead of “39”. These numbers range from 410xxxx to 412xxxx, what I believe to be the typical October to December pattern. And then we are into 1960 with 6 digit numbers beginning with “6” as discussed earlier.
The table summarises my analysis of the serial numbers from this period but does not include the earlier Yashica 635 and Yashica 44 style consecutive series numbers before they too adopted this system from mid1958.
Model  Serial No.  Year  Month  

From 
To 
From 
To 

Yashica all  79xxxx 
1957 
September 

YashicaMat  579xxxx 
579xxx 
1957 
Late Sep 

Yashica LM  710xxxx 
711xxxx 
1957 
October 
November 
Yashica all  5710xxxx 
5712xxxx 
1957 
October 
December 
Yashicaflex all  3210xxxx 
3212xxxx 
1957 
October 
December 
Yashica all  581xxxx 
589xxxx 
1958 
January 
September 
Yashicaflex all  331xxxx 
338xxxx 
1958 
January 
August 
All  389xxxx 
1958 
September 

All  3810xxxx 
3812xxxx 
1958 
October 
December 
All  391xxxx 
399xxxx 
1959 
January 
September 
All  3910xxxx 
1959 
October 

All  410xxxx 
412xxxx 
1959 
October 
December 
All  61xxxx 
69xxxx 
1960 
January 
September 
Yashica A  11611xxxx 
1960 
November 

Yashica 635  13611xxxx 
1960 
November 

YashicaMat  14610xxxx 
1960 
October 

Yashica MatLM  15609xxxx 
15611xxxx 
1960 
September 
November 
Yashica 44LM  16609xxxx 
16611xxxx 
1960 
September 
November 
It could be argued that I have simply put the number patterns in an order that fits my theory. As I explain further down, the order of the patterns fell out from placing cameras (several thousand) into my database based on known factors, trim and other variations. The possible date code link between the patterns came later, in 2014 in fact.
Serial Numbers from 1961 to 1980
Alpha prefixed 7 digit serial numbers and also 7 digit Yashica Mat124 and Yashica Mat124G numbers (note, does not apply to 6 digit prefixed Yashica D Hong Kong production or the last 6 digit Yashica Mat124G numbers both of which appear to be simply consecutive), appear to incorporate a date code which is a bit more obvious than the preceding period. All the relevant numbers follow the pattern and generally match the release and end dates of a particular model, but there are some date discrepancies which I will discuss later. Basically, the alpha prefix identifies the model, sometimes obviously and for some models, seemingly chosen at random. The first digit from the left is the year, e.g., both 1961 and 1971 will be “1” (this leads to numbers being repeated and is exactly what has happened for certain long running models). The second and third digits are the month, i.e., from “01” through to “12”. As far as I can tell, the last 4 digits is likely to be a straight numerical sequence which probably counts from zero at the start of each month. Therefore we can refine the general formula in Decoding Serial Numbers to:
Model Identifier  Year  Month  Monthly Count from Zero 

Alpha sequence, later nothing 
1 digit 
2 digits 
4 digits 
For example, the serial number MT 9050490 breaks down to 9050490 and translates to YashicaMat, 1969, May, 490th made that month.
If we accept the commonly quoted 16 year life span of the Yashica Mat124G and 573,362 produced, that is an average production of approximately 2,986 per month. Not all, perhaps any, models will have achieved similar average rates. In most cases, the “monthly production” will seem plausible with the first digit from the left of the four digit sequence rarely reaching “2” and often remaining “0” or “1”. But there are exceptions, the early Yashica MatEM reaching over 9,000 in both its first two months of production of February and March 1964. My database has quite a lot of examples from both months but there are no examples from April through to and including August. My interpretation is that Yashica produced an initial stockpile for the model's release in June 1964. Similar things have happened on a smaller scale at other times.
7 Digit Numbers  Correlation to Model Release and End Dates
This numbering system started in early 1961. The Yashica A, B, 635, D, 44A, 44LM, YashicaMat and Yashica MatLM were already in production. Their new numbers started with “10xxxxx”. Please note that the “Start Year” (apart from 1961) represents the commonly quoted dates which could be either start of production or onsale release dates. The “End Year” (apart from Yashica Mat124G) represent the commonly quoted end dates which could be either end of production or end of official sales. In the first case, there could still be a lot of stock to dispose of. So, in some cases, there won't be an exact match between the serial number range and the dates of a models life. Also, some dates, particularly end dates may be questionable.
Model  Start Year 
End Year 
First Serial No. Found 
Last Serial No. Found 
Match or Comment No. 

Yashica A  1961 
1969 
A 1040xxx 
A 8060xxx 
1 
YashicaMat  1961 
1971 
MT 1030xxx 
MT 3030xxx 
2 
Yashica 635  1961 
1964 
ST 1010xxx 
ST 4050xxx 
3 
Yashica 635  1964 
1973 
SX 4061xxx 
SX 1081xxx 
4 
Yashica B  1961 
1961 
B 1080xxx 
B 1120xxx 
5 
Yashica D  1961 
1973 
D 1020xxx 
D 1092xxx 
6 
Yashica 44A  1961 
1965 
FA 1020xxx 
FA 5060xxx 
7 
Yashica 44LM  1961 
1965 
FL 1020xxx 
FL 5090xxx 
8 
Yashica MatLM  1961 
1964 
MTL 1020xxx 
MTL 4011xxx 
9 
Yashica E  1964 
1965 
YE 3060xxx 
YE 4070xxx 
10 
Yashica MatEM  1964 
1967 
EM 4023xxx 
EM 7070xxx 
Match 
Yashica 24  1965 
1967 
L 5110xxx 
L 7111xxx 
Match 
Yashica 12  1967 
1968 
R 7020xxx 
R 8050xxx 
Match 
Yashica Mat124  1968 
1970 
7100xxx 
0072xxx 
11 
Yashica Mat124G  1970 
1980 
0091xxx 
0021xxx 
12 
Comments
 The last Yashica A serial number starts with “8” which suggests a production end date of 1968 as opposed to some sources which suggest 1969. However, there is nothing to say that a camera starting with “9” won't turn up.
 The YashicaMat was thought to come to an end in 1971 but the serial numbers suggest that 1973 was more likely. Note however, that after September 1971, there is a 13 month gap in my database until October 1972, then there are seven cameras between then and March 1973 so production may have stopped and then restarted.
 The end of the Yashica 635 “ST” series and start of the “SX” series appears to be a smooth transition between May and June in 1964. However, there is one camera with a very clear number, ST 6120xxx. Unlike the cameras around it, it still has 2 screws in the back and the lens numbers suggest a camera from between the last unprefixed number, 670xxx, and the first prefixed number, ST 1010xxx. I think this camera has a new nameplate from the official Yashica spare parts system (see below).
 According to the Kyocera/Yashica documentation quoted by the website “A Partial History of Yashica TLRs”, Yashica 635 sales are said to have ended in 1972 or 1973 (I don't understand the table). The last serial number I have found is from 1971. Later numbers may turn up or production may have ended earlier with enough stock for a further year or two of sales but that document also contains some obvious errors.
 The Yashica B end date is not known but it does appear in a 1961 Swedish brochure.
 The Yashica D also seems to have finished up to two years short but there are the Hong Kong cameras which may have come after Japanese production finished  they certainly have the very last trim features. My own thought is that 1972 might be about right. Note that after 10 years, the numbers appear to be repeating themselves. That is the failing of using a single digit year code.
 I haven't found a reliable end date for the Yashica 44A. By trim, it is earlier than the last of the 44LM examples and the 44LM appears in at least one late 1965 brochure. Now I have also found a 1965 ad with both models appearing. Interestingly, no cameras starting with “FA 4xxxxxx” have turned up so far, i.e. no 1964 production.
 The Yashica 44LM seems to match up nicely but there are three cameras not included in the table , FL 5090xxx, FL 6111xxx and FL 6120xxx, that seem to come up to 15 months after the previous example. The cameras themselves have much earlier features and lens numbers than the cameras around them and I believe these are other examples with parts from the official Yashica spare parts system (see below).
 The Yashica MatLM looks like another match but I have not included the last six cameras. Of these, the very last three are MTL 4110xxx (would still be a match but came 10 months after the previous cameras) and two with MTL 5080xxx numbers very close to each other. The three have earlier lens serial numbers and features than the cameras around them, including the screws near the control wheel exposure window which disappeared on all affected models in the first half of 1962. It is harder to tell with the other three but by lens serial numbers and the screws near the exposure window (only visible on one), they are also unlikely to match their serial numbers. In my view, the exposure meters on the six cameras, and hence serial numbers, have all been replaced from the official Yashica spare parts system (see below). Consequently, the last production numbers are likely to be in the MTL 4011xxx range.
 The Yashica E serial numbers suggest a production start in June 1963, a long way in advance of the claimed 1964 and September 1964 at that. In the Yashica E entry on the 66 Models page is concrete evidence that the release was actually February 1964 or earlier and some evidence that it was late 1963, better but still somewhat short. Perhaps introduction was delayed for some reason. The end date of 1964 matches some claims (another claims 1966) but it does appear with a Yashica 24 in a brochure suggesting late 1965, at least for any inventory stock. The Yashica 24 was claimed to be released in December 1965 and the first serial number is from October 1965, a close match. The Yashica E is the only model with claimed dates in significant conflict with my numbering theory. Whether it blows the theory out of the water, or there was something else going on, is for you to decide.
 The first Yashica Mat124 serial number puts it into 1967 rather than 1968 but it is October 1967 so with production starting early, it probably still fits comfortably with a claimed February 1968 release.
 The 1970 start date for the Yashica Mat124G appears to be a match. The 1980 end date is simply the changeover to the new 6 digit consecutive numbering system.
The Yashica Spares System Theory  the Impact on Serial Numbers
Except for serial numbers located inside cameras, Yashica had a habit of sticking them on easily removable components which could either be damaged in a fall or like exposure meters, be susceptible to failure. I am aware that there have been “new, old stock” nameplate, exposure meters and even Yashica E flash assemblies for sale. How did Yashica deal with the serial number issues? No one really knows apart from the fact that the new items definitely have new serial numbers. I can think of three possibilities:
Theory 1
You have a camera bought new in 1960. You have dropped it and Yashica has supplied a new focusing hood and nameplate which now has a 1965 serial number. Later something else goes wrong and you walk in to the local Yashica service centre and ask for a new part. You are asked for a serial number  how will Yashica know it's a 1960 camera with a 1965 serial number?
Based on the Yashica 635, Yashica 44LM and Yashica MatLM examples above, it is possible that Yashica used higher serial numbers for their spares than they anticipated producing by their date code. That wouldn't identify the camera correctly but would flag that the number had been changed. Note that nine of possibly ten cameras affected have exposure meters on which the serial number is located. Exposure meters are both vulnerable and also likely to suffer the occasional fault.
Theory 2
This is a similar theory but instead of wanting to identify that a camera has a new serial number, Yashica didn't want to get its camera count out of order. With or without date code, each serial number includes a sequence number which is an easy way of keeping tabs on total production. If nameplates or exposure meters were simply whipped off the assembly line, that could have created problems for keeping track of production and/or accounting for other parts destined for assembly. Therefore numbered parts destined to be spares were given a “future” number anticipated to be beyond normal production.
Theory 3
Or, more simply, perhaps the spares were produced after production ended and the date code reflects the date that the part was made or distributed. Once production was finished, it probably was finished complete with a supply of parts for the spares department but it is possible that numbers were added afterwards, just before dispatch from the factory warehousing.
These are simply guesses based on my logic which may have absolutely nothing to do with reality. What we do know for certain is that seven cameras have higher serial numbers outside the limits of apparent production and these do not fit neatly within the serial number patterns that work for every other camera in the period. Plus there are another three cameras at the upper end of the Yashica MatLM serial number range with earlier trim and lens serial numbers thus making a total of ten cameras which have earlier features than all the cameras around them so that they definitely do not match their very late numbers. Therefore, even without factoring in the date code, there is something very different about these examples. But there is one more.
This camera is a Yashica LM from 1957 from before the commencement of the date code in September. It has a body serial number inside near the feed spool, 119xxx, and lens numbers 816xxx (taking) and 812xxx (viewing), all consistent with each other and with the camera's trim. It also has a serial number on the nameplate flap over the exposure meter, just like the last LM examples. This is 3920xxx. Obviously, the nameplate flap has been replaced. By date code, the date is February 1959. Of the last four Yashica LM examples in my database, three have 5810xxx and one has 5820xxx serial numbers  January and February 1958. It doesn’t really prove/disprove anything to do with a date code but it does lend credibility to the idea that spare parts had higher serial numbers than production cameras (we can see from trim and lens serial numbers of other models that 582xxxx numbers come well before 392xxxx numbers).
Since I wrote this section, contributor Tom Heckhaus has been through his Yashica bits and pieces. In the 1980s, Yashica in the US sold off its stock of TLR spares and Tom was one of the purchasers. He has three Yashica MatEM focusing hood assemblies. Until now, the highest EM serial number in my database was EM 7070xxx, July 1967 by my reckoning, and very close to the claimed end date of August 1968. Tom's three hoods have the following numbers EM 9120238, EM 9120277 and EM 9120286, all suggesting December 1969. One of these is below (the number is hard to read but zoomed in, EM 91202xx is clear enough):
(Image courtesy of Tom Heckhaus)
Do These Patterns and Date Codes Exist for Other Format Yashica Models?
The short answer is “I don't know for sure but in some cases, probably yes”. Towards the end of the 1950s, Yashica started to move into 35 mm cameras and then subminiature with the shortlived Y16. It is likely that initially at least, the same rules applied for most models but at some point, there could well have been a divergence for any number of reasons. I have no reason to track anything except the TLRs but I have collected a few sample serial numbers for three nonTLR models and contributor Chris Whelan has analysed the serial numbers of the Pentamatic 35 mm SLR released in early 1960. This is what has been discovered.
The Y16 was released in 1959. It didn't last long, I'm not sure how long but in 1964, Yashica released the 16EE using a different cassette system (Minolta type). A correspondent has given me eleven serial numbers. Ten are typical of Yashica TLR numbers from 1959 and the eleventh is typical of 1960 numbers. But there is a catch. The 397xxxx numbers are a direct match, the “39” I believe equating to the year 1959, the “7” to July, and the “xxxx” the production number for the month. Starting with what I believe is August, all Y16 numbers gain one additional digit so that e.g., August becomes 398xxxxx and Dec becomes 412xxxxx. The extra digit could mean anything but I believe that the production number was increased to allow for more than 9999 cameras in a month. In most cases, the digit after the month was 0 but in one case, it was 1 and the total sequence was 10393. I think a monthly output spike of 10,393 is probably a realistic production number. The 1960 number is 67xxxxx.
The FlashOSet 35 mm model was released in 1961, the same year that TLR serial numbers adopted an alpha prefix system with standardised 7 digit numbering. The original FlashOSet cameras have a “T” prefix with 7 digit numbers starting with “1” and going as high as “112” (1961, December) before “20” (1962 and any of the first nine months) appear. This model was replaced by the improved FlashOSet II in 1962. The model II has the new prefix “FII”. I have only seen numbers beginning with “2” and these go as high as “212”. In other words, these numbers are completely consistent with the TLR pattern.
A number of sites say that the Minister D 35 mm model was released “around 1963”. The Yashica Guy thinks it was in 1964. I have thirteen serial numbers. The first five cameras have “MD” prefixes. The first camera has a 7 digit number MD 402xxxx (1964, February) which is followed by MD 403xxxx (1964, March). However, the third and fourth cameras have 8 digit numbers MD 4041xxxx and MD 4050xxxx (1964, April and May). It is possible that the extra digit, after what I think is the month code, represents another increase in capacity for recording production numbers as perhaps it was with the Y16. If so, it was temporary because the next number I have is my 7 digit MD 7090451. Did the model last until September 1967? Possibly, it does appear in a 1967 US brochure. The next number is 6 digits beginning with “H”, H 110xxx, i.e. most probably Hong Kong production without a date code and a very similar number to the Hong Kong Yashica Ds. This is followed by another, H 136291. Then there are five 6 digit numbers with a “T” prefix, T 050xxx to T 808xxx. What these mean and where they fit, I have no idea. Cameras with both “MD” and “T” prefixes have “Japan” stamped next to the serial number on the top plate. Cameras with “H” prefix don't have either Japan, or Hong Kong, on the top or bottom plate or anywhere else discernible.
The Pentamatic serial numbers look quite different but seem to be based on similar principles. Chris Whelan has so far recorded 12 serial numbers and I have added just one for a total of 13. As Chris has postulated, so far, it looks very plausible that the numbers, unusually for Yashica, start with the month, followed by year and then by a cumulative production number instead of a monthly total. Chris and I are still debating whether the year code is just that or whether it includes both year and model.
Serial Numbers Found  All TLR Models
In “66 Models” and “44 Models”, I try to make sense of serial numbers in terms of trim changes. In regard to the serial number table below, you will have to trust me that my Microsoft Excel spreadsheet with individual lines for each serial number and columns for all the possible trim and feature permutations paints a very clear picture of the correct order and age of cameras. I will be the first to admit that it may not be 100% accurate but I think that it is pretty close. Please remember that the serial numbers below are the numbers that I have found so far  they are an indicator only. The serial numbers of the lenses don't directly correlate to the body numbers range  they may start earlier and finish later or vice versa, be out of order or relate to cameras that I don't have body numbers for, i.e., they are indicative of the lens numbers that you may find near the listed body numbers, if that makes sense.
In the first column, I have separated models by shutter type, Pigeonflexes by the Yashima name change and the Hong Kong version of the Yashica D. In the last column, I have identified lens names for models where a change occurred. For both the Yashica A and D, I have highlighted the blocks of serial numbers in which coloured cameras may be found  in those blocks, there is only the odd black example. I have also added a “Year” column. For serial numbers which I believe include a date code, i.e. generally from September 1957 to early 1980, the year will be the actual year for the block of numbers. In all other cases, cameras from 1957 and earlier and cameras from 1980 and later, the year will be based on the year of the model release and any known changes, e.g. a trim change, end date etc. Those dates may include date ranges, e.g. “19534” and can only be considered to be approximations. To make it clearer, I have shown those years in italics:
Model 
Year

Body Serial No. Range 
No. 
Typical Taking Lens Serial Numbers 

From 
To 

66 Models  
Pigeonflex (Yashima Seiki) 
1953 
257xxx 
257xxx 
3 
243xxx 
1953 
215xxx 
217xxx 
10 
243xxx247xxx  
Pigeonflex (Yashima Kogaku Seiki) 
19534 
218xxx 
223xxx 
25 
248xxx267xxx 
19534 
253xxx 
256xxx 
10 
258xxx268xxx  
Pigeonflex (no maker name) 
1954 
? 
26xxxx 
4 
268xxx273xxx 
Yashimaflex (NKS) 
1953 
220xxx 
260xxx 
5 
262xxx265xxx 
Yashima Flex (NKS) 
1953 
34xxx 
35xxx 
7 
269xxx274xxx 
Yashima Flex (NKSTB) 
19534 
37xxx 
44xxx 
15 
275xxx289xxx 
Yashima Flex (NKSFB) 
1954 
44xxx 
44xxx 
4 
290xxx291xxx 
Yashica Flex B  1954 
45xxx 
48xxx 
9 
287xxx, 291xxx300xxx, 22xxx27xxx 
19545 
50xxx 
54xxx 
18 
27xxx35xxx  
Yashica Flex S (NKSFB) 
1954 
29xxx 
30xxx 
9 
287xxx297xxx (TriLausar) 
1954 
30xxx 
34xxx 
24 
224xxx231xxx (Heliotar)  
Yashicaflex S (Copal) 
1955 
30xxx 
31xxx 
25 
232xxx237xxx (Heliotar) 
1955 
200xxx 
1 
234xxx (Heliotar)  
19557 
67xxx 
72xxx 
33 
238xxx250xxx (Heliotar)  
Yashicaflex AI (Y.S.K.)  1954 
? 
12xxx 
3 
12xxx 
Yashicaflex AI (Copal)  1954 
12xxx 
14xxx 
6 
14xxx, 31xxx40xxx 
1955 
61xxx 
65xxx 
13 
57xxx82xxx, 100xxx  
19556 
79xxx 
80xxx 
3 
201xxx202xxx  
19567  112xxx 
138xxx 
27 
114xxx134xxx, 225xxx467xxx, 761xxx771xxx, 805xxx  
Yashicaflex AII (Y.S.K.)  1954 
17xxx 
20xxx 
13 
18xxx30xxx 
Yashicaflex AII (Copal)  1954 
24xxx 
30xxx 
21 
31xxx50xxx 
19556 
61xxx 
122xxx 
68 
49xxx129xxx, 202xxx242xxx, 300xxx320xxx  
19567 
213xxx 
214xxx 
9 
328xxx425xxx, 660xxx769xxx  
Yashicaflex ASII  1954 
30126 
User manual 
1 
29991 
1954 
30xxx 
1 
38xxx  
19556 
81xxx 
83xxx 
16 
63xxx90xxx, 109xxx129xxx, 202xxx227xxx  
19567 
19xxx 
23xxx 
32 
127xxx186xxx, 202xxx242xxx, 361xxx886xxx  
MolfoReflex  1955 
8xxx 
8xxx 
4 
100xxx201xxx 
1955 
114xxx 
114xxx 
4 
114xxx204xxx  
19556 
31xxx 
31xxx 
12 
128xxx409xxx  
Yashicaflex C  19557 
501xxx 
598xxx 
101 
117xxx119xxx, 160xxx163xxx, 227xxx809xxx 
Yashicaflex
AIII 
1955 
118xxx 
1 
215xxx  
Yashica Rookie  19567 
197xxx 
233xxx 
27 
171xxx182xxx, 259xxx260xxx, 348xxx774xxx 
Yashica HiMec  1956 
30xxx 
? 
2 
237xxx 
Yashica LM  19567 
100xxx 
127xxx 
81 
268xxx285xxx, 425xxx557xxx, 600xxx982xxx 
1957 
790xxx 
791xxx 
11 
883xxx981xxx  
1957 
7100xxx 
7110xxx 
3 
913xxx915xxx  
1957 
57110xxx 
57120xxx 
10 
256xxx, 405xxx416xxx, 924xxx968xxx  
1958 
5810xxx 
5820xxx 
4 
212xxx4xxxxx  
Yashica C  19567 
800xxx 
829xxx 
39 
267xxx296xxx, 410xxx859xxx 
1957 
791xxx 
793xxx 
5 
890xxx894xxx  
1957 
57100xxx 
57122xxx 
6 
915xxx976xxx  
1958 
5880xxx 
5880xxx 
2 
244xxx, 421xxx  
1958 
38101xxx 
1 
442xxx  
Yashica A  19567 
30xxx 
67xxx 
28 
295xxx, 370xxx864xxx (Yashimar) 
1957 
790xxx 
793xxx 
4 
873xxx900xxx (Yashimar)  
1957 
57110xxx 
5712xxx 
6 
957xxx960xxx (Yashimar)  
1958 
5840xxx 
5883xxx 
9 
215xxx, 241xxx245xxx, 410xxx427xxx (Yashimar)  
1958 
38100xxx 
38121xxx 
4 
254xxx, 425xxx462xxx (Yashimar)  
1959 
3911xxx 
3911xxx 
2 
271xxx472xxx (Yashimar)  
1959 
3940xxx 
3991xxx 
28 
293xxx513xxx (Yashikor)  
1959 
39102xxx 
1 
? (Yashikor)  
1960 
611xxx 
641xxx 
5 
570xxx595xxx (Yashikor)  
1960 
116110xxx 
1 
653xxx (Yashikor)  
1961 
A 1040xxx 
A 1041xxx 
3 
694xxx697xxx (Yashikor)  
1962 
A 2030xxx 
A 2112xxx 
9 
765xxx946xxx (Yashikor)  
1963 
A 3010xxx 
A 3101xxx 
4 
962xxx, 105xxx (Yashikor)  
1964 
A 4031xxx 
A 4070xxx 
2 
171xxx222xxx (Yashikor)  
1965 
A 5020xxx 
A 5071xxx 
3 
298xxx342xxx (Yashikor)  
1966 
A 6020xxx 
A 6120xxx 
4 
688xxx691xxx (Yashikor)  
1967 
A 7041xxx 
A 7110xxx 
3 
727xxx791xxx (Yashikor)  
1968 
A 8041xxx 
A 8061xxx 
9 
817xxx845xxx (Yashikor)  
Yashicaflex A2 (Citizen MXV) 
19567 
3xxx 
15xxx 
19 
523xxx524xxx, 603xxx610xxx, 199xxx, 987xxx, 418xxx, 510xxx 
1957 
19xxx 
1 
296xxx  
Yashicaflex A2 (Copal MXV) 
1957 
16xxx 
18xxx 
8 
417xxx616xxx, 271xxx 
1957 
330xxx 
1 

YashicaMat (Copal MX) 
1957 
57xxx 
59xxx 
5 
19xxx20xxx, 40xxx (75 Lumaxar) 
YashicaMat (Copal MXV) 
1957 
59xxx 
65xxx 
23 
21xxx24xxx, 33xxx, 40xxx42xxx, 61xxx (75 Lumaxar) 
1957 
64xxx 
84xxx 
76 
25xxx48xxx, 71xxx74xxx, 80xxx100xxx (80 Lumaxar)  
1957 
790xxx 
791xxx 
5 
97xxx100xxx (80 Lumaxar)  
1957 
5790xxx 
5790xxx 
2 
107xxx (80 Lumaxar)  
1957 
57100xxx 
57120xxx 
14 
99xxx122xxx (80 Lumaxar)  
1958 
5870xxx 
5881xxx 
10 
200xxx204xxx (Yashinon)  
1958 
3890xxx 
3891xxx 
4 
204xxx207xxx (Yashinon)  
1958 
38101xxx 
38121xxx 
9 
209xxx216xxx (Yashinon)  
1959 
3910xxx 
3911xxx 
3 
217xxx218xxx (Yashinon)  
1959 
4110xxx 
4120xxx 
4 
219xxx (Yashinon)  
1960 
630xxx 
661xxx 
10 
223xxx231xxx (Yashinon)  
1960 
146100xxx 
146100706 
2 
229xxx239xxx (Yashinon)  
1961 
MT 1030xxx 
MT 1120xxx 
5 
222xxx262xxx (Yashinon)  
1962 
MT 2021xxx 
MT 2081xxx 
6 
306xxx346xxx (Yashinon)  
1963 
MT 3010xxx 
MT 3060xxx 
5 
387xxx488xxx (Yashinon)  
1964 
MT 4100xxx 
1 
?  
1965 
MT 5020xxx 
MT 5120xxx 
6 
478xxx521xxx (Yashinon)  
1966 
MT 6050xxx 
MT 6121xxx 
6 
532xxx668xxx (Yashinon)  
1967 
MT 7021xxx 
MT 7100xxx 
6 
696xxx776xxx (Yashinon)  
1968 
MT 8010xxx 
MT 8100xxx 
7 
797xxx818xxx (Yashinon)  
1969 
MT 9050xxx 
MT 9111xxx 
2 
904xxx942xxx (Yashinon)  
1970 
MT 0010xxx 
1 
940xxx (Yashinon)  
1970 
MT 0060xxx 
MT 0110xxx 
3 
986xxx1027xxx (f/2.8 viewing lens)  
1971 
MT 1010xxx 
MT 1090xxx 
12 
705xxx743xxx, 1027xxx1037xxx (f/2.8 viewing lens)  
1972 
MT 2010xxx 
MT 2123xxx 
5 
773xxx806xxx, 1078xxx1092xxx (f/2.8 viewing lens)  
1973 
MT 3030xxx 
1 
1105xxx (f/2.8 viewing lens)  
Yashicaflex
unknown model 
1957 
xxxx 
? 
3 
272xxx298xxx, 519xxx 
1957 
28xxx 
? 
2 
522xxx538xxx  
1957 
121xxx 
? 
2 
541xxx  
Yashicaflex AS (new model) 
1957 
19xxx 
27xxx 
27 
440xxx448xxx, 614xxx, 701xxx877xxx 
Yashicaflex B (new model) 
1957 
59xxx 
71xxx 
14 
701xxx, 820xxx847xxx 
1957 
80xxx 
88xxx 
6 
852xxx873xxx  
1957 
7xxxxx 
790xxx 
4 
834xxx876xxx  
1957 
32100xxx 
32120xxx 
15 
835xxx, 909xxx992xxx  
1958 
3312xxx 
3371xxx 
13 
200xxx219xxx, 249xxx, 407xxx  
1958 
3890xxx 
3891xxx 
4 
418xxx448xxx  
1958 
38100xxx 
1 
418xxx448xxx  
Yashicaflex A (new model) 
1957 
10xxx 
11xxx 
4 
807xxx882xxx 
1957 
64xxx 
69xxx 
4 
700xxx824xxx 

1957 
83xxx 
86xxx 
2 
839xxx  
1957 
290xxx 
290xxx 
2 
884xxx  
1957 
32100xxx 
32111xxx 
4 
89xxxx997xxx, 213xxx  
1958 
3350xxx 
3380xxx 
5 
213xxx419xxx  
1958 
38110xxx 
1 
458xxx  
Yashica 635  1958 
56602 
User manual 
1 
981xxx (Yashikor) 
1958 
58xxx 
61xxx 
5 
982xxx992xxx, 210xxx (Yashikor)  
1958 
5860xxx 
5870xxx 
2 
238xxx, 405xxx (Yashikor)  
1958 
3890xxx 
1 
249xxx (Yashikor)  
1958 
38100xxx 
38102xxx 
3 
253xxx258xxx, 444xxx449xxx (Yashikor)  
1959 
3910xxx 
393xxxx 
6 
276xxx, 477xxx488xxx (Yashikor)  
1959 
4110xxx 
4121xxx 
7 
535xxx559xxx (Yashikor)  
1960 
641xxx 
670xxx 
5 
601xxx642xxx (Yashikor)  
1960 
136110xxx 
1 
657xxx (Yashikor)  
1961 
ST 1010xxx 
ST 1110xxx 
6 
676xxx692xxx (Yashikor)  
1962 
ST 2030xxx 
ST 2121xxx 
7 
827xxx967xxx (Yashikor)  
1963 
ST 3020xxx 
ST 3121xxx 
3 
974xxx, 150xxx171xxx (Yashikor)  
1964 
ST 4031xxx 
ST 4050xxx 
5 
175xxx187xxx (Yashikor)  
1964 
SX 4061xxx 
SX 4121xxx 
7 
197xxx291xxx (Yashikor)  
1965 
SX 5010xxx 
SX 5090xxx 
11 
290xxx362xxx (Yashikor)  
1966 
SX 6021xxx 
SX 6112xxx 
14 
383xxx447xxx, 634xxx688xxx (Yashikor)  
1967 
SX 7010xxx 
SX 7122xxx 
15 
451xxx, 715xxx810xxx (Yashikor)  
1968 
SX 8020xxx 
SX 8110xxx 
6 
77xxxx890xxx (Yashikor)  
1969 
SX 9010xxx 
SX 9110xxx 
8 
888xxx948xxx (Yashikor)  
1970 
SX 0030xxx 
SX 0080xxx 
6 
971xxx994xxx (Yashikor)  
1970 
SX 0091xxx 
SX 0120xxx 
6 
998xxx1014xxx (Yashinon)  
1971 
SX 1061xxx 
SX 1081xxx 
2 
1036xxx1061xxx, 782723 (Yashinon)  
Yashica B  1958 
38100xxx 
38110xxx 
3 
253xxx, 458xxx462xxx 
1959 
393xxxx 
3950xxx 
9 
491xxx503xxx, 289xxx300xxx  
1959 
4120xxx 
1 
?  
1960 
620xxx 
660xxx 
7 
573xxx628xxx  
1961 
B 1080xxx 
B 1120xxx 
2 
750xxx794xxx  
Yashica D  1958 
38110xxx 
38121xxx 
12 
452xxx464xxx, 258xxx260xxx (Yashikor) 
1959 
3910xxx 
3990xxx 
30 
269xxx301xxx, 480xxx485xxx, 517xxx525xxx (Yashikor)  
1959 
4100xxx 
4102xxx 
5 
533xxx539xxx (Yashikor)  
1960 
611xxx 
641xxx 
16 
564xxx598xxx (Yashikor)  
1960 
? 
? 
2 
648xxx666xxx (Yashikor)  
1961 
D 1020xxx 
D 1090xxx 
8 
680xxx741xxx (Yashikor)  
1962 
D 2021xxx 
D 2110xxx 
14 
809xxx945xxx (Yashikor)  
1963 
D 3010xxx 
D 3120xxx 
12 
957xxx998xxx, 149xxx163xxx (Yashikor)  
1964 
D 4030xxx 
D 4111xxx 
12 
172xxx270xxx (Yashikor)  
1965 
D 5031xxx 
D 5120xxx 
9 
305xxx376xxx (Yashikor)  
1966 
D 6010xxx 
D 6091xxx 
17 
384xxx668xxx (Yashikor)  
1967 
D 7011xxx 
D 7121xxx 
20 
714xxx825xxx (Yashikor)  
1968 
D 8011xxx 
D 8120xxx 
20 
775xxx888xxx (Yashikor)  
1969 
D 9010xxx 
D 9121xxx 
9 
893xxx949xxx (Yashikor)  
1970 
D 0030xxx 
D 0061xxx 
8 
764xxx, 931xxx1001xxx (Yashikor)  
1970 
D 0070xxx 
D 0122xxx 
15 
980xxx1032xxx (Yashinon)  
1971 
D 1021xxx 
D 1092xxx 
22 
1016xxx1066xxx (Yashinon)  
Yashica D Hong Kong 
1971 
H 103xxx 
H 113xxx 
8 
724xxx741xxx, 1036xxx, 788xxx793xxx (Yashinon) 
Yashica AIII  1959 
3933xxx 
3962xxx 
7 
212xxx494xxx 
1959 
39100xxx 
1 
525xxx  
1959 
4110xxx 
4120xxx 
6 
510xxx553xxx  
1960 
611xxx 
680xxx 
7 
562xxx643xxx  
Yashica Auto  1959 
3930xxx 
3950xxx 
22 
200xxx212xxx 
Yashica MatLM  1959 
4110043 
User manual 
1 
220002 
1960 
620xxx 
680xxx 
19 
221xxx237xxx  
1960 
156090xxx 
156110xxx 
2 
240xxx246xxx  
1961 
MTL 1020xxx 
MTL 1121xxx 
20 
247xxx297xxx  
1962 
MTL 2010xxx 
MTL 2123xxx 
36 
299xxx395xxx  
1963 
MTL 3011xxx 
MTL 3121xxx 
19 
396xxx428xxx  
1964 
MTL 4010xxx 
MTL 4011xxx 
5 
423xxx435xxx  
Yashica E  1963 
YE 3060xxx 
YE 3121xxx 
23 
No lens numbers 
1964 
YE 4010xxx 
YE 4070xxx 
13 
No lens numbers  
Yashica MatEM  1964 
EM 4023xxx 
EM 4121xxx 
29 
EM 4010xxxEM 4020xxx, 438xxx472xxx 
1965 
EM 5010xxx 
EM 5110xxx 
18 
478xxx515xxx  
1966 
EM 6010xxx 
EM 6120xxx 
22 
514xxx673xxx  
1967 
EM 7010xxx 
EM 7070xxx 
6 
675xxx706xxx  
Yashica 24  1965 
L 5100xxx 
L 5121xxx 
19 
508xxx515xxx 
1966 
L 6010xxx 
L 6120xxx 
21 
512xxx674xxx  
1967 
L 7020xxx 
L 7111xxx 
24 
672xxx781xxx  
Yashica 12  1967 
R 7020xxx 
R 7120xxx 
34 
543xxx, 671xxx778xxx 
1968 
R 8020xxx 
R 8050xxx 
5 
797xxx801xxx  
Yashica Mat124  1967 
7100xxx 
7124xxx 
14 
706xxx, 776xxx810xxx 
1968 
8010xxx 
8123xxx 
38 
772xxx849xxx  
1969 
9012xxx 
9122xxx 
42 
850xxx943xxx  
1970 
0010xxx 
0072xxx 
30 
938xxx985xxx  
Yashica Mat124G  1970 
0091xxx 
0120xxx 
13 
990xxx1021xxx 
1971 
1010xxx 
1124xxx 
31 
1026xxx1076xxx, 702xxx774xxx  
1972 
2022xxx 
2120xxx 
15 
764xxx814xxx, 1066xxx1079xxx  
1973 
3013xxx 
3121xxx 
19 
1100xxx1141xxx  
1974 
4020xxx 
4123xxx 
8 
1143xxx1170xxx  
1975 
5020xxx 
5121xxx 
17 
No lens numbers  
1976 
6012xxx 
6103xxx 
12 
No lens numbers  
1977 
7024xxx 
7114xxx 
15 
No lens numbers  
1978 
8010xxx 
8122xxx 
10 
No lens numbers  
1979 
9010xxx 
9123xxx 
9 
No lens numbers  
1980 
0021xxx 
0031xxx 
2 
No lens numbers  
19806 
053xxx 
235xxx 
83 
No lens numbers  
Yashica Mat124B  c1981 
107xxx 
168xxx 
15 
No lens numbers 
44 Models  
Yashica 44  1958 
17xxx 
22xxx 
38 
333xxx345xxx 
1958 
5850xxx 
5890xxx 
39 
347xxx426xxx, 531xxx  
1958 
? 
? 
3 
366xxx, 425xxx426xxx  
1958 
3890xxx 
3895xxx 
12 
426xxx434xxx, 365xxx366xxx  
1958 
? 
? 
7 
372xxx436xxx  
1958 
38101xxx 
38115xxx 
14 
437xxx446xxx, 371xxx373xxx  
1959 
3921xxx 
3972xxx 
16 
384xxx387xxx, 454xxx491xxx, 602xxx 604xxx  
1960 
? 
1 
604xxx  
1960 
650xxx 
690xxx 
6 
492xxx, 547xxx554xxx  
Yashica 44A  1959 
? 
? 
5 
349xxx388xxx 
1959 
3940xxx 
3993xxx 
77 
388xxx399xxx, 460xxx498xxx, 500xxx501xxx, 600xxx605xxx  
1959 
4100xxx 
4112xxx 
16 
507xxx516xxx  
1960 
620xxx 
650xxx 
9 
527xxx540xxx, 415xxx  
1961 
FA 1020xxx 
FA 1121xxx 
26 
682xxx789xxx  
1962 
FA 2020xxx 
FA 2120xxx 
31 
812xxx951xxx  
1963 
FA 3040xxx 
FA 3111xxx 
14 
951xxx999xxx, 107xxx113xxx  
1965 
FA 5020xxx 
FA 5070xxx 
6 
295xxx338xxx  
Yashica 44LM  1959 
3930009 
1 
200022 Camera in user manual  
1959 
3950xxx 
3984xxx 
30 
201xxx203xxx, 466xxx489xxx, 504xxx507xxx  
1959 
39100xxx 
39101xxx 
7 
206xxx207xxx, 505xxx541xxx  
1959 
4110xxx 
4111xxx 
4 
520xxx524xxx  
1960 
610xxx 
660xxx 
24 
489xxx, 522xxx552xxx, 669xxx  
1960 
166090xxx 
166110xxx 
17 
550xxx559xxx, 685xxx  
1961 
FL 1020xxx 
FL 1120xxx 
17 
390xxx, 685xxx, 727xxx791xxx  
1962 
FL 2010xxx 
FL 2120xxx 
24 
802xxx962xxx  
1963 
FL 3010xxx 
FL 3110xxx 
12 
960xxx982xxx, 111xxx179xxx, 200xxx250xxx  
1964 
FL 4010xxx 
FL 4110xxx 
13 
200xxx351xxx  
1965 
FL 5010xxx 
FL 5070xxx 
11 
232xxx390xxx  
Out of Sequence (higher) Serial Numbers  Yashica Spares?  
Yashica 635  ? 
ST 6120xxx 
1 
665xxx  
Yashica MatLM  ? 
MTL 4012xxx 
MTL 4110xxx 
4 
263xxx368xxx 
? 
MTL 5080xxx 
MTL 5080xxx 
2 
231xxx, 263xxx  
Yashica 44LM  ? 
FL 5090xxx 
FL 6120xxx 
3 
669xxx, 740xxx 
Note: “No.” is the number of cameras found in the serial number range. Sometimes it may include cameras with serial numbers just outside the range if the serial number is not visible but lens numbers were consistent. In other words, like the rest of the table, it is a guide only. Don't total this column and expect it to equal the total numbers of cameras in my database quoted elsewhere. In theory it should but my database grows more quickly than I can find time to update this table. I do try to make sure that significant serial numbers or patterns are updated.
Location of Body Serial Numbers
The Pigeonflex, Yashima Flex, most Yashicaflexes and Yashica TLRs have their body serial number on the top edge of the nameplate. However, these are the exceptions:
 Yashica Flex S (most NKSFB examples, except very last): on meter flap face.
 Yashicaflex S (all Copal versions): inside near feed spool.
 Yashicaflex ASI & ASII: inside near feed spool (example shown in user manual is earliest serial number and has number on flap like the early Yashica Flex S).
 Yashica HiMec: inside near feed spool.
 Yashica LM (early): inside near feed spool.
 Yashica LM (late): on meter flap face.
 Yashica MatEM (early): on focusing knob side strap holder (because of meter windows, very hard to see in photos).
 Yashica MatEM (late, most examples): on rear of hood (because of meter windows).
 Yashica 24, 12, Mat124 and Mat124G: on rear of hood (because of meter windows).
In summary, all Yashima/ Yashica TLRs , have their serial numbers on the top edge of the nameplate except for models with exposure meters when this arrangement is not possible (all except Yashica MatLM and Yashica 44LM).