I just finished charging my a/c system on my '72 CS with a 134a retrofit kit. It can't get much easier. The system was already empty when I bought the car, so I just put on the new fittings and charged it up. We'll see what happens after a little time, but for now its putting out 41F at the vents. For $35 (Walmart) and freon that won't hurt the atmosphere if it leaks out, I figured I'd try it.