ABC;
You definately have 39's. The yellow one looks like it has a Chevy engine. GMC didn't have any tags on the side of the cowl. The ID tag was located on the inside of the firewall behind the engine.
The green truck appears to have a newer engine based on the rocker arm cover, so that is not a good indicator. GMC had a smoothe cover with the GMC script logo on top.
Since the orginal GMC 228 CID was longer than a Chevy 216 CID, the radiator was moved forward about 2 inches, thus the lights were also placed in a different location on the radiator housing. The headlight stands were smaller as that of a 1937 Chevy.
I have been restoring my 39 GMC for a few years (too many) and most mechniclal parts are shared with the Chevy except for the engine. I believe the springs had an extra leaf also. But what I do know, it is much easier to find sheetmetal parts for Chevy. So restore the chevy.
With all the input from everyone you will be an expert IDing these trucks.
Happy restoring,
Jim
