A/c Hose O-rings Needed

[PaulRV6]

I want to replace all the o-rings in the A/C system while converting the freon.
Can I get these from the GM dealer and if so what are the P/N's?
I really only need the ones for the evaporator line and both compressor lines. With the P/N's given will they be good for R134A? Thanks

paul