transmission swap?
 

saw an ad for a 83 300sd with 'new' transmission. is this the same transmission i have in my 83 300 d turbo? thank you.

There are serial and type numbers on the transmissions... you could get the seller to check his and you check yours... that is really the only way to know if it is exactly the same.... I think I have seen deals where three types were used in one year .... so would not want to put a lot of work and money into a swap without being very sure....

Most of the transmission is the same but the 126/SD has an inductive drive for the speedo while the 123/D has a mechanical/gear drive for the speedo. Apparently it's a lot of work to open the tail housing to swap parts. Might be easier to put a 126 speedo in your 123 cluster if it's possible.

The transmission numbers are a guide. I got my 81 SD (sold) with 290K miles. The transmission was a 722.309 out of a 280E but with a 126 tail housing. I replaced it with a junkyard 722.315 out of a 300Dt also with a 126 tail housing. Someone out there's rebuilding transmissions and using any old case.

Sixto
91 300SE
87 300SDL
83 300SD