Ok just got back home from checking this thing out. Yes it does have 6 bolt wheels. The serial # tag is missing from the right side of the cowl. Gauges are missing too. It had a crank out windshield with the wipers above. The headlights happen to be on the front seat which is I think a big clue. They look very similar to the 2 panels pictured on here. However instead of a parking light on top there is just a chrome fin. I'm thinking this means its a 39 truck and originaly it had parking lights and headlights together in the one fixture. Currently it does have sealed beams in the housings but I know lots of the late 30s vehicles got converted in the 40s. I did find an engine head in the back for a flathead 6. Wouldnt both the chevy and GMC trucks have an OHV 6? Of course being in the junkyard so long both the headlights or the engine head could have wandered in from some other vehicle.
Ed