(Like I posted at the forbidden board):
Happened to me too, these cars don't have very strong axles...
http://boards.rennlist.com/upload/DSC0000004.JPG
http://boards.rennlist.com/upload/DSC0000005.JPG
I'd definately go with the Porsche part. Sometimes parts really are interchangable, but just because something bolts up doesn't mean it's the same part. Very good example is the front control arms of early 944s, do NOT go non Porsche on those, ditto for the bushings...
Ahmet