Regarding the A/C comments... converting a GMR-12 system to R-134 can give very good results if done properly. Yes, R-12 is a better refrigerant than R-134, but I do not want to get into all those technical details. Follow all the recommended procedures (found on the Internet)for a conversion (I will only summarizethe steps here) - flush the evaporator and dry, flush the condenser and dry, change orifice tube, change accumulator, add the correct amount of oil back into the system (BVA100 recommended)readjust low pressure switch, change all the o-rings with compatible R-134 o-rings using Nylog for reassembly and get as much old oil as possible out of the compressor (if possible).

The real key to the conversion (and better A/C performance) is to use a different orifice tube in the GM system and the low pressure switch set correctly. I converted a '92 Camaro RS using the above procedure and had very good results. The Camaro had an original.072" orifice tube. During the conversion I used a blue Ford .068" orifice tube. In addition, you will need to readjust the low pressure switch (if adjustable) on the accumulator, so the compressor cycles at about 19~20psi. You can also buy a new low pressure switch already preadjusted / presetfor R-134. If done correctly, the conversion will provide good long lasting results. If you really want to go all out, and take full advantage of the R-134, you may want to look into a parallel flow condenser.

CG