S4 and S5 motors are completely different for the record.

In 89 and 90 there were GXL's... In 91 there were only the 3 models (vert, turbo, coupe). Before that there was also the GTU model and the GTUs.

To clarify which parts he listed would work from an S4 on a S5:

Alternator - will work, but actually has a lower amperage output.

AFM - Will not work, not even the same design.

Intake stuff - Almost everything on the intake including the intake itself was completely different.

Tranny crossmember - S5's had a different tranny crossmember.

Motor Mounts - are the same...

Didnt really wanna resurrect an old thread, but thought the information could be helpful to anyone else. Most parts are not interchangeable between the S4 and S5 models.

- Chris