I installed a new 12v motor inside my old 6v housing for the harrison heater in my 50.
Purchased the 12 motor from Truck Shop in orange ca.(few years ago) It did not have the studs comming out the back of the motor.
It had a 2 wires, black and orange. You can change direction shaft turned depending on what wire you used for hot. Ground the other wire.
My old 6v motor was toast so I had no problem gutting it.
...pic... If my original 6v was still good I would have just used it with a voltage reducer.
Original 6v delco motor will be superior than any replacemet motor. IMHO
Good Luck
