If I'm correct from what I'm reading, the engine is a '38 24 stud or newer, so obviously not the original engine. The intake is not correct for the 24 stud engine, but is correct for 37 truck with 21 stud.
With my recently re-built 94 carb and fuel pump (AC) from Ken ct, I decided to install them today. A quick trip to ACE Hardware for the brass plug and I was in business. (see pic) I trimmed a couple gaskets, complements of ken ct and installed the carb. Without going into details about the carb and Ken's findings, I DO NOT recommend purchasing a re-built carb from Mac's! Next was the fuel pump.
FYI Old...Bill, I also installed a new fuel flex line from Robert. Thanks for the tip though. (see pic)
Ken, as you said, the carb was plug & play, no adjustments required. The engine cranks right over; idles nice and smooth.