Please check this out, I tried to remove all of the confusion on the ZF and BW automatic transmissions as there was speculation on shift linkages and dipstick location which I have corrected.
e9coupe.com
Automatic Transmissions
Both the e3 sedans and the e9 coupes used the same automatic transmissions but they changed during model year production. Initially the ZF 3HP-20 was installed in the early 2500 and 2800 sedans as well as in the 2800CS and later in the 2.5CS. It was replaced by the similar ZF 3HP-22 in the...
e9coupe.com