I have a set of near new (about 10K miles) stock 2001 S4 shocks and springs (all four corners). Can they be used on B5 A4 as well?
I plan to sell them and need to know possible applications.

Yes they will...

I had S4 OEM suspension on my Frist Audi. A 1996 2.8. I was a little disappointed because the car didn't lower the way I expected. other wise it was a direct fit.

the front will sit up higher due to the difference in front distributed weight on an S4 due to a larger engine.