I thought all quattros got 5 cyl engines regardless of 80 or 90 designation so the tranny would mate to the engine. Do you know of quattro Audi 80's that were not 5 cyl? As far as 1988 Audi 90 FWD 5 cyl vs. 1988 Audi 80 quattro 5 cyl I really do not know. I would be surprised if they were different. Eric