OK you KNOW the voltage is low, so next question is the regulator internal or external?

If external, then I'd get one and put it in. If that's not it then keep the old one in the glove box.

Another good thing to do would be to swap in new pig tail for the alternator, regulator or both.

If you do, then solder and shrink wrap the connections, no point making a new problem down the road by using a cheap crimp connector.