First it's an 8v unless someone has done an engine swap. The 16v did not show up until 86' and due to it having DOHC on the intake manifold I think you would kind of know as soon as you popped the hood. There are 55, 65 and 90 amp alternators which will fit your engine which VW used from the factory (maybe not on your model but will fit). Why do you ask about options for a replacement or an up-grade? Is it stereo related? If not then stay with the 55 or 65, the 90 would be overkill even with A/C.
A gentleman is selling me a 65 amp digifant 2 8v w/o AC alternator for a GTI.
Will it work on the Rabbit?
It should but there could be some differences. The pulley I think is the same but if not you will have to swap over the current one. The wiring could be different depending on the make of the alternator, some use post connections and some have a plug on connection.