New Alternator Questions?

I agree with Dave. Sounds like your car had a dual field alt. installed previously and the car is only setup for a single field style so the 2nd field had to be grounded on the alternator that was on it to make it work. If your wiring harness only has one small green wire and the big black wire to hook up to the alt. just hook them up and your done.

If the car your refering to is the one in your avatar it looks like a 69 Dart so it is a single field system.