AC questions for 1990

[Mystic ZR-1]

Does anyone have a PN and source (GM or ?) for the R12 Low and High service connection valve cores (similar to the ones used on tires/wheels) and the tool needed for removal/installation? R12 and R134a cores are different. The R134a valve core tool I have does not fit. The low pressure core is probably just loose causing it to leak when the valve cap is removed and a the small screwdriver trick doesn't work... The local Chevy dealer (who wouldn't give me the PN and there's no PN in my old GM parts book just NS...) said they're NLA. I've checked several local auto parts places with the same results. I'm leary of what I've found on the Internet for obvious reasons. The dealer has R12 in stock (that's why I went there) unfortunately for $$$, otherwise I avoid the place like the plague...

Looks like it's time to convert R12 to R134a?

Conversion questions:


Is the the AC-Delco 15-1645 accumulator the correct one? Does it come with a R12 or R134a service fitting?


Orifice filter, AC-Delco 15-5754, 15-5151 or ? Not shown, no PN in the good old parts book.


R12 to R134a service connection adapters, do the R12 cores remain in place or are they replaced with a a new valve in the adapter? See above question...


I've obtained all the needed o-rings, believe it or not, not NLA but $$$!


The tentative plan, if I convert, is to replace the needed parts myself and then have the dealer (OH, that hurts...) evacuate and fill the system with the correct oil and refrigerant because I don't have the needed equipment.


Any suggestions?


Thanks,
Doug
...it's starting to get hot here in CT...