Well, bad news #1. the tailgate rear window motor is locked up tighter than a bull’s azz! Tried with an external factory switch and the tailgate key switch and nothing but a little buzz.
Well, Forget my bad news #1! It was suggested to try and put power directly to the motor bypassing the internal harness. Doing this the motor raises and lowers the arms as it should. So something is amiss either within the harness or the window limiter. I can make another harness if need be; I might even have a spare limiter in storage.
EDIT: The window limiter from this tailgate was the culprit. Luckily I have a spare from a 63 harness.