differences in chain boxes

[echocanyons]

I need to replace a chain box on an engine that had a rear end collision.

I am wondering if they are all interchangable or if there are ceratin years that are better.

I am only referring to the housing not the cover.

Thanks
Kelly

[ChrisBennet]

There are some differences. I can give you a list but it would save me some effort if you could you give me the year or flavor (911, 964, 993) of the motor in question.
-Chris

[echocanyons]

the engine is a 81 3.0

Kelly

[Henry Schmidt]

Any aluminum housing from 77-88 will work.
There are some earlier mag housings will work but they a not as strong.

[echocanyons]

Thats what I was lookin for thanks a bunch!