1975 450 SLC - Died on me while I was driving home. Tried to restart, but dead battery. When I jump start the car, it fires right up and runs great until I disconnect the jumper cables, then sputters and dies.

I pulled the alternator and had it tested. the shop said it was good. The battery does hold a charge, so I'm guessing that the voltage regulator is the culprit.

Any ideas?? If so, WHERE IS IT? I can't seem to locate it, and the Hayes manual I've got doesn't specify the location.

Also, could it be another component?? THANKS!!