New (not NOS) r12 parts are still available at parts stores if you are worry about still use the original one. Just request for it. I’m sure 4Seasons still makes them. When I got my expansion valve and dryer I asked to Rockauto to be specific for r134 (for the later upgrade I was to make) on parts request. They told me the PNs for 4 seasons between R12 and R134 parts were diff by just 1 number. Let’s say! R134 PNs were 3xxxxxx and R12 were 2xxxxxx

…or something like that. That was long time ago.

So ask the dealers or straight to 4seasons