Originally posted by mercedesny
What also has me confused is that the thing screws in (has threads on it). I thought the transmission vacuum modulator was bolted in (remove a couple bolts and it slides in with an o-ring seal)?
If it has threads, it's the kind that goes in the right side of the trans near the back. There are two different 123 chassis transmissions. One for non-turbo cars, one for the turbo cars. If the car is a 1981 300D (non-turbo) that is the correct part.