Check out the wiring diagram from this website.
http://www.tocmp.com/tOCMP/wiring/Po...ing/index.html
go to the bottom to 64 and check it out. did u have the dash wiring out?? need some more detail as what u had out and what u did to it. I just had all my 64 harness out last year, Non vert. Not a voltage reg problem. Also taillights don't go through turn signal switch.
Rick