I had the opportunity to do this on my 86 Bronco (have had since 1/98). It's a good idea. The conversion was not as costly as I thought it would be. The kit contains a new evaporator, R-134 fittings, O-rings, and compressor oil. I've probably forgotten something, but the kits can be had through JC Whitney if nowhere else. The biggest part is evacuating the old system (you'll probably need a professional for this). After that, a quick compressor oil change, put the new parts on and you're ready for the new, cheap, and plentiful R-134 refrigerant. You also get the added benefit of environmental friendliness. It also works just as good if not better than R-12.