I kinda like those GMC factory quirks. Since the harness I bought is for a chevy, the negative ground seems easier to install. I'll have to see if I can find some wiring diagrams to help me through the process. The instructions are vague at best.

I tested that motor with both 6 and 12 volt sources. It seemed to like the 12 volt... not to fast, not to slow. Pushes a little more air at 12 volts. It would probably work pretty well with a selector switch. This heater motor is going to be hard to replace cause the shaft is long on both sides. It has a squirel cage on one side, and a 4 blade propeller on the other.

Anyway, I'll see what I can come up with. I have a 100 amp chrome alternater I was planning to use.

Cletus and Atomarc thanks for the replies