1953 GMC Master Parts Book shows parts for "positive type ventilation" as far back as 1939 on larger than pickup sized models. Here is a picture from a US Army deuce and a half maintenance manual. This valve was fed from the top of the valve cover. Instead of being throw away, you can disassemble, clean and re-assemble.
'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.
