W123 Transmission Question?
 

Question about W123 transmissions...

I have an 81 300D non-turbo sedan and on my data card the transmission number is 02 127905. I know the "02" denotes that it is an automatic transmission but is the rest of the number a serial number specific to my transmission only? Or is that number a general part number for these transmissions? For example, if I'm looking for a replacement transmission, would I be looking for another one with the number 02 127905 or am the only one that has that number because it's my transmissions serial number?

I ask because my transmission is shot and I found another 81 300D sedan and the transmission number on that data card is 02 134567. I'm pretty sure they are the same transmissions, they are from the same year/era but the different numbers through my off. Then I figured it was more likely a serial number specific to the vehicle and not a part number. Can anyone confirm?

So that is most likely the vacuum modulator style and serial number.
If you crawl under the car on the passenger side (Right hand side in the case yours is not a LH drive US spec car)

There was a member who made a lovely guide on adjusting the modulators and such on these, and this is the information from that on identifying your transmission:

You'll see numbers right below where the bowden cable enters the trans case, it may take a little cleaning, but it will say something like 126 2700801 722.303 02 054545
The first batch of numbers 126 2700801 is the vehicle type, 722.303 is the transmission type, 02 is the vacuum modulator type, and the 054545 is the serial number of the transmssion.