[s-cars] C4 front strut differences

[Mike Fitton]

Did some digging in the ETKA in the front suspension department.  I've 
noticed that, in the US, the S4/S6 front wheel bearing housing (which 
I've lately come to call the struckle) is p/n 4A0 412 025 AB (026 for 
the other side, of course) while the 100/A6 got 4A0 412 025 AA (and 026 
for the right).  I know that a different suffix doesn't necessarily mean 
the parts are interchangable.  Things were much more complicated in the 
European analogs, but that's not important right now.

Basically I'm looking for an extra set of uprights.  With 100s and A6s 
presumably being more common, can anyone confirm their interchangability 
or do I need to get S-car uprights?

-Cheers!
Mike