Wrong Alternator?

It's easy to test enough to at least get an idea of the trouble. Start by taking a jumper wire and remove the green field wire. Check with a multimeter to ground and make sure there is continuity. Hook your jumper wire / alligator clip lead to the battery, and touch it to the alternator field terminal. In subdued light you should be able to see a small spark.

Next connect that terminal to the battery with jumper. Start car, slowly bring up RPM. Ammeter should start to show a charge. Best to also monitor battery voltage