Those doors are earlier than '51 (no vent windows).

It has been converted to 12 volt (has a ballast resistor).

What is that thing that looks like a radiator cap about 12" to the passenger's side of the ignition coil?

Handbrake indicates earlier than 51 cab.

As Ed pointed out, a Chevy engine. The Chevy engine is about 1 1/2" shorter back to front, so the fan will be further from the radiator than stock. If you do a lot of low speed driving in a hot climate a fan shroud may be necessary to keep the coolant temp down.

Using your cab's serial number and the table below, which year would your cab be?
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Last edited by Bill Hanlon; 04/25/2023 4:06 AM.
'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.