What alternator do I have?

That's a 72 and up dual field alternator that someone converted to single field to match your wiring. Grounding one field connection with the red coiled wire was an attempt to do that. Hopefully nothing fried. I would convert the harness to the later regulator when you replace your dead alternator, or go with an original single field alternator. You need a basic voltmeter that reads DC volts. Home Depot has them.