The supplied drawing above shows the pressure line going into the top of the filter can and the drain line coming out the bottom. Seems to me like the filter can would drain down when the engine wasn't running. That's how it works on my GMC, but it isn't a Chevy.
'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.
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