most decent audis have RWD oriented engines but have a FWD gearbox, kind of a regular rwd gearbox, diff and prop all into one box driving the front wheels (crackheads or what??)
no idea at all about cost but would be interesting conversion. come to think of it, is it the RS8 or something that has the 6.2 twin turbo V10? probably a small fortune to aquire but you could pinch the 4wd system as well. what are you shoehorning this into again...? certainly would make a very unique car! that or the fordracing usa aluminator engine, 32valve quad cam all ali supercharges firebreather of a v8, 700bhp and 600ft/lb anyone?? it gains extra kudos because its out of the ford competition drift mustang!
do you have 5 grand to spend on a tremec 6 spd?
i should probably shut up now!