Cranks but won't start. Unplug ground at field spade on Alternator and it starts?

This was the voltage regulator that had been on there for 20 years that died 3 weeks back and was replaced by the mechanical one from Napa:

https://shop.advanceautoparts.com/p...gulator-raa1052/12450617-P?selectedStore=2623

The local parts store says they can have one this afternoon.