[MARKDTN]

By "modern" compressor do you mean it has an R4 (short radial) or it has the HT6 like most '96 up trucks?

The R4 with a serpentine system puts the back of the compressor in a similar place to an original A6 with v-belts. You may have to bend the tubes slightly.

The biggest issue is the POA valve and R134. Some people adjust it to work with R134. Some replace it and make it a hybrid cycling system with an expansion valve. Andy's picture shows using '77-87 accumulator and orifice tube system cycling system.

I would just use R12 and keep the POA.