I painted myself in the same corner last year. The clutch was making noise so I got a new compressor, after installing it I realized there was no way I could run all the old dirty parts thru my new compressor. The 134 is made to replace 12 the trick is to replace all the seals with ones that work with the gas and flush the system. I did refer work in my 20's around the time 12 got outlawed, on the slower days we would just play with things for fun. We would put the wrong gases in systems just to see if we could make it work. The 134 will work you just have to prep for it.
