I have bought a 1971 GTO 400 4 speed muncie with according to the math a 4:66.1 gear. Numbers off the ring gear are 9A42 GM ZP 169 2 it has a roughly 1/8 inch spacer behind the ring gear. The only numbers on the carrier are T67 and there fins cast on the ring gear side of the carrier. the passenger axle tube has SD stamped on it and nothing else. The center section has 130 on the passenger side and BH on the drivers side. Any help identifying this rear end would be greatly appreciated. I was told it may be a judge but we all know that story Ill wait for PHS to tell me what it is. thanks again in advance Bob Ok I figured out its an olds O rear end but I still have things that dont add up like it has c-clip axles is there some way these interchange ?