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Good day fellow forum folks!!, I have a seiko question. It’s actually a bunch of questions.


i know the first 4 numbers are the caliber code, ie 6139, but the last 4 on the dial often differ from the case back. Sometimes by only 1 number but sometime by the entire sequence. Would the first be considered the dial code, containing information like date, color, etc. and the other code information on the actual case, style, origin, etc? Would an extreme difference in the 2 codes indicate a swapped case back?

Am I correct in believing that a interpretation of the serial number will only yield the date of manufacture of the CASE, as well as the region but nothing really to do with the dial?

i received a bunch of watches strictly intended for fixer uppers and while 2 of them have 6139 dials, the movements are 6138B’s. My inventory begins to runneth over;).

Anyway, thanks for any insight!!
 

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The case back serial number indicates the final casing date.


Many times, though not always, the same date code (first digit = last digit of year, next digit is the month 1-9 then O, N, D) is printed on the back side of the dial which you can only see when taking the dial off the movement.


For an example, here is an April 1979 6139-6013 (last month known in 6139 production) dial showing the 94 dial code.
 

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Quite often the last 4 numbers on the dial match the last 4 on the case back - other times the very last digit is different.
This is usually attributable to different market regions, ie the japanese market (JDM) will usually end in a 0, whereas the US market version will end in 9. The reason for this is that the day wheels will be in different languages (Kanji+English vs English+Spanish), and those will have there own differing serial numbers.
The dials, and all other parts, will be identical and will all be printed with the same number - usually the Japanese one.
There are exceptions of course - the 6119-6020 and 6023 have slightly different case designs and vastly different crowns, but otherwise appear similar.
I've often found the dial date to be the preceding or same month to the case date.
If numbers don't match that might not be proof of a dial and case being swapped out.
I usually check google images with both numbers to see what that throws up.
 
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