I have that alt dismantled right now, it was choked with oil residue. The removal is pretty easy, I think I did it from above by pulling the air pump out of the way first. This alt is marked 115amp although as I understand it there was a 90amp option also, so check yours first.

A new voltage regulator is fine if your slip rings are in good shape, otherwise you might be back to square one.

steve a

__________________
Steve A
92 W140 OM603
97 VW Jetta TDI
90 Passat variant TDI 6 speed MT
94 Chevy K1500 6.5TD
05 E320 CDI
+ others