I've had good luck with Vintage Air products. The trick is the A/C brackets and drive for our old engines. On original engines I will usually build a bracket and find a "piggyback" type sheave for the generator and run off of it. If you re clever enough this can be done without hacking up the truck. I actually installed an A/C unit in a model A ford that I had built many years ago. 40 horses of fury at the crank.... it would go from 45 mph down to 35 when the compressor kicked. What was nice about it was during parades. The war department and her mom would be sitting in the rumble seat baking in the Texas sun while they where handing out trinkets to kids, and I would have the windars up and a windbreaker on. Everytime they looked into the back windar I would do the hands rubbing together I'm so cold bit... Good times.