I doubt that they are all the same unit from 89-93...Gotta figure out what unit you do have and go from there if you want to repair it...If you are going to replace the unit I don't think it matters which one you use...I would see about using the FX15 I think it is...And get your system changed over to the R12, it is not that spendy to do...They just purge your system and change some O-Rings...You can still get the old stuff, but it is much more costly, although some are willing to pay the extra bux cuz the old stuff is actually cooler..
Brad