I can't really tell which compressor I need. If you go to RockAuto https://www.rockauto.com/en/catalog/chevrolet,1987,r20+suburban,7.4l+454cid+v8,1300835,heat+&+air+conditioning,a/c+compressor,6628 it lists several as a fit and look similar (although some can be discounted because the pulleys...