Up to '98, '99-'00, & '01 Alternators; Differences

[FusiliJerry]

Besides amperage, what are the differences between these apparently disparate applications? I will eventually be upgrading my 01's alternator with a Singer and want to give a friend my high-quality OEM replacement.

 

[75SV1]

The later alternators wire(s) are a plug in. The earlier ones have a bolt on.