Heater Box Wires

[Greg S THomas]

I picked up a heater box for my 73 Dart at MOPARS in the park this summer and now have gathered the rest of the parts I need to install it. The Heater box fits perfectly in the car but the wiring clip in the car has to slots on it and the heater box has 3. I looked up other heater boxes on Ebay and they all have just two wires.
Does anyone know what the difference is between the boxes with 2 and 3 wires and if I will be able to get the box I have with 3 wires to work in my car?

Thanks

 

[Greg S THomas]

I did some research and I think I have a 3 speed fan Heater resistor and need a 2 speed fan resistor. Does anyone one know where I can get a 2 speed resistor?