Hey John,
       On my '90 AC, the high-pressure side fitting is located inside the
plastic housing, on the driver side rear.  Follow the hose coming from the
non-fitting (discharge) side of the compressor, you will see it goes over to
the left and up through the rear deck.  Take the panel off, and you will see
it.
       If you have cabinets or any of that stuff, then I don't know.

BIll Marshall
85 GL Tiico with retrofitted 90 AC
Bradenton FL