A/C Compressor valve

I'm in the process of replacing the Sanden SD 508 style A/C compressor in my 1987 3.2 US spec Cab, and the schrader valve in the inlet fitting seems to have decided to quit sealing. Anyone know of replacement number or size for it, or the sizes of the two threaded fittings on the inlet port if I just replace the whole thing? I would like to avoid spending the almost $300 dollars the parts houses seem to want for what should be about a $15 dollar fitting. TIA!

 

Thanks Mike! I'll give them a look.