Does anyone know if a 95 LeSabre has R-12 or R-134a in the air conditioner and if it is still R-12, is there a retrofit kit available?

It has R134-a. You should see quick connect couplers on the high and low side lines instead of threaded connectors.

I'm 100% positive its 134a like hotZ28 said.

If you're ever in doubt, there should be a sticker on the front underhood crossmember over the radiator on a piece of plastic. This sticker has warnings, belt routing and somewhere should say which refrigerant to use.