forum.audiv8.com Foren English Audi V8 Forum Converting A/C system to later gas

Posting again as the previous post appears to have a problem.

I have 3 V8s.

The 1990 and 1991 cars with the older single display control panel are both original R12 spec. Both need to be recharged.
The later 1993 car was Dealer converted to R134, but there is little information about what this entails. Is it possible to simply use later gas with few problems?

Is there an easy to follow procedure, documented parts, etc, for both systems?

Secondary question
The earlier type of compressor. My 1990 had a compressor clutch failure. Lots of smoke, noise, fumes. I ended up parking the car for a while as I couldn't get a tool to pull the clutch off. It appears to be M24x1.5 thread. Supposedly, clutches are easily obtained.
I've swapped in a complete spare used compressor, although I do have a brand new still boxed up. I don't want to unseal the new one until I know what I need to do about gas.
Could someone identify the actual puller/tool. the set that I ordered is actually not compatible.