How similar are the E34 M20s and the E30 M20s?

[jplacson]

Other than the engine, what other similarities do these 2 serieses share with each other? Electricals? Tranny? Drivetrain?

All I know is that the older E34s have the same steering wheel fitment.

[Derek A.]

The motors are basically identical. I do know that the later usage of these engines saw a change to the Motronic control unit - so chances are that there is some electrical differences in the later engine.

[Rigmaster]

ETK shows 2 different part numbers for the E34 M20 (525i) and E30 M20 (325i/is) engines.....I know the difference(s) must be small, I'm assuming something like motor mount holes or similar??

Does anyone know for sure how the engines differ???

Bret