Alternator OEM Volvo or GENERAL MOTORS

Those alternators are damn near bulletproof, it’s the voltage regulators that crap out. If it were me, I’d keep the OEM unit, replace the pulley, and swap out the voltage regulator while I was at it.

Here is a stock Mk2 65 amp alternator (top) and the generic one-wire GM alternator (bottom). They're physically the same size, and the posts are almost identical in length. The GM fan is indented in the center though, and the VW one is flat. I used the GM fan, cause my stocker is disgusting, lol. I swapped the VW hardware/pulley over, since the GM pulley was obviously no good (flat, not offset).