Originally Posted by DieselJim

I am starting down the course of overhauling my a/c system. I am deciding what parts I should acquire. I have 126 technical manual cd, haynes heating and air techbook, and a venturi vacuum pump. I know I need a drier, manifold gauge, o-rings, 4 cans of r-12(I have my certification ), flushing solution(mineral oil), possibly a flush gun for my compressor and refrigerant oil. I have been tempted to just change the compressor while I am in there. The current compressor works but I have no idea how well and how old it is. Will any r4 harrison compressor from that era work. I see several on ebay marketed towards GM car owners. Are all r4 harrison compressors the same?

I have read several of the threads in this forum. The main question here is about the compressor.