[Ez-Bone]

Originally Posted by mistertate

If I remember right the big difference between the steel and aluminum trailing arms is that the spring plate mount moves inboard/outboard between the two types. That's what makes the torsion tube change, I just can't remember if it changes on early or late aluminum.
The easist way to figure it all out is go look for corresponding part numbers here:

Early Cars
https://techinfo.porsche.com/techinfo/pdf/en-us/catalogues/944_USA_82_85_KATALOG.pdf

Late Cars
https://techinfo.porsche.com/techinfo/pdf/en-us/catalogues/944_USA_82_85_KATALOG.pdf

Both of those are for '85 it seems :P Don't see anything for 85 and earlier