I removed an expansion valve from a 1989 560SEL. It had an R-134 sticker. The system is R-12. The car was R-12 from the factory. I know for sure it has never been changed. Your replacement valve will be marked R-134. The system operating pressure for R-12 and R-134 are similar. The R-134 valve will work fine. Stay with the R-12. Good Luck.