Any manual 2wd gearbox (5 or 6 speed) from an Audi A4 or A6 will bolt straight onto the V8 which means gearbox codes 016, 01A, 01E, 01X etc
The 01E is probably the strongest of the units mentioned above with the 01A being the weakest.
Quattro gearbox will fit as well, but are much less desirable as they need modification to remove the rear diff output and are inherently weaker when used as a 2wd unit.
Hilly