Early BMW transmission question

[RonDwyer]

I think I want to keep the automatic in my 77 530i while I upgrade to an 89 motronic 535 engine, BUT, I don't know if the bell housings on the motronic slush boxes are a bolt-on to the earlier ones. For now I'm sticking with the automatic because my daughter is afraid of 5-speeds so that one will sit in the garage for a few more years...

Are the bell housings readily interchangeable?

[Mike W.]

If you are really talking an 89 535 engine, no problems, that version of Motronic takes it's crank input off the front pulley area, not the flywheel like earlier Motronic. If you are just concerned about the bellhousing bolting up, a M30 is a M30, bellhousing wise, they are all the same. If you are looking at an earlier Motronic engine that does take it's input off the flywheel, you would need a bellhousing/pump off an 82-83 5/6/733, they used the same 3HP22 transmission, but with the sensors in the bellhousing.