You will need 12 volts for the compressor clutch, and also the blower motor. There is a chance you can get some sort of electrical thingy to convert from 6 to 12, I think they make them to run newer radios, but not sure if they are powerful enough for AC.
I have not installed or bought the system for my 48, but the research I have done leads me toward the Classic Auto Air Street Rod Cooler II unit. I think, after a phone conversation with them, that it is better unit than the one they sell as a "perfect fit" kit for my truck.
I think I can do a neater job of installing the street rod unit than the other one in the kit.
