Do you still have any of the "failed" regulators? If you can send me one (preferably a Delco-Remy) I can do a continuity check on it to see if it has any internal circuit problems. There's not likely to be anything wrong with a generator that will "motor' and also charge with the field circuit grounded. A properly polarized generator will produce about 1/2 to 3/4 volts at the armature terminal with all the wiring disconnected, running at a fast idle. That's called "residual voltage".
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!