I'm refurbishing my heater box because of leaky core, rust, and installation of new seals. When pulling the assembly out of my car, I noticed that there were 3 electrical connections coming out of the resistor. It looked like there may have been a fourth but I can't find a wire that would tap into it. Can anyone else with a 66 3 speed blower motor comfirm this on their car? 3 Prong or 4 Prong?

 

You use the threepin type. The fourth was for an air conditioner system but that type of systemwas not included in early Mustangs.
JIm

 

ya, that fourth connection looks like it's been snapped off at the base. It's not used.

 

I thought so. Thanks guys. I have to say that pulling the heater core out of the car was one of those things that I "thought" would be a pain but it ended up being about as simple as filling up at the gas station. Anyhow. . . . back to work