This is quite surprising. I wonder if maybe the lines have been changed after it came from the factory as an R12 car?

FWIW, by Federal Law, the fittings are supposed to match the refrigerant therein. For cars that have been modified by individuals, this means NOTHING in that there might be any refrigerant under the Sun in the system regardless of the fittings. For the Mfg.'s OTOH I can't imagine them not matching the fittings with the installed refrigerant.

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2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

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