thanks for the reply pennyman1. im thinking i will probably try R152a first seeing the success others have been having but if not i will do all of those things you mentioned. if i go with R134a however i will probably use the dealer add on system since R134a expansion valves are cheap and the system i pulled is missing it anyway plus if that sanden SD508 is unhappy with R134a i bet finding a drop in one that will would be easy since it seems to be a widely used modular compressor. either way ill be left with an extra system once im done.just for curiosity would this be something that would be wanted by someone here on the forum?