I am gearing up to swap a 454 into my '85 Burb next week. I think I have everything figured out except the A/C. The Burb currently has a 350 and uses the smaller type a/c compressor (R4) and it is located on the driver's side of the engine. Some of these vehicles came with the longer a/c compressor (A6) mounted on the driver's side. Additionally, I have seen the R4 compressor mounted on the passenger side when a 454 was present in the 2 wheel drives. The engine I am going to use has the brackets for the A6 compressor on the drivers side. Is one or the other compressor better? When the system is reassembled R132 freon will be used. Is one or the other better suited for this? Does anyone know if there is a 454 A/C bracket available for the R4 compressor to mount on the driver's side?