The 65 would have had a "Delcotron" first generation alternator with an external regulator. I seem to remember some sort of shunt circuit that comes off the regulator wiring that turns the "ammeter" into some sort of "charge/no charge" indicator. I'm headed out of town today on a road trip, but I'll try to see if I have a circuit diagram I can scan and email to you as soon as I get back. I believe I've got an old Motor manual stashed away that might have that circuit illustrated.
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!