It must be O-rings. AHRRRRRR, I did it very slowly last time. Obviously, not carefull enough. Thanks guys for the advice. The leak seem to be from the fitting/O rings at the front of the expansion valve.
Donald, I already replaced most of the stuff you listed, including the evaporator. The expansion valve is cheap comparing to the rest of the AC system but, it is a pain to replace.
I guess is time for R134 conversion and another expansion valve.
Thanks for the advice.

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J.H.
'86 300E