Terry,
Interesting question on the heater blower motor. Your truck was originally 6 volt, positive ground. It is undoubtly (my guess) 12 volt, negative ground now. Some folks run the 6 volt blower motor on 12 volts, then switch motors when it blows up.
They make heavy duty voltage reducers so you can retain the 6 volt motor and run it on the new voltage. Usually the motor runs faster and noisier, even when run through the reducer.
Is your motor a two speed setup, switched by some two pole LO/HI fan switch? I am not sure what the SOP is when switching from positive to negative ground on a heater motor...maybe nothing!
To get net on this thing, I would say either your switch is broken/wired wrong, or the motor is roached. This doesn't help you at all, but this problem would need more research, ideally with a meter to "see" what the voltage is doing.
I don't know if a polarity issue could make this motor run backwards and make it appear to be marginally functional.
I have no clue on your wipers.
Stuart
