I had a 1966 cuda. The voltage regulator was a single relay that would burn out in 10-12k. In the early 70's crysler used an external solid state reg which was a power transistor. I had to un-ground the one brush and send it to the collector of the NPN power transistor, emitter went to ground and the base voltage determined how hard the transistor conducted.
I'll google Lejay Co and see if there is something I can use.