I have a 66. My heater box was worthless when I took it out. I found a really nice used 64/65 box here in town. It does not have the resistor hole. My question is can I just cut a hole, add a resistor and be good to go? My understanding is that the resistor controls the fan.

Thanks, Jeff

 

Yes, the boxes are the same, except for the hole.

Of course all the wiring and resistor from the original 66 setup is different from 'early' box with the 3 wire motor, so you will need the 2 wire motor from the 66 box.

Yes, the resistor is for the fan speed selection on 2 wire fan motors.