I went back and re-read the original post. Seems to me that Craig may be referring to the threaded opening on the filter base that I point to in the picture below. If so, that is where the oil pressure sensor (if he has an electric oil pressure gauge) or the tubing that connects to the oil pressure gauge (if he has a mechanical oil pressure gauge - most likely) plugs in.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
