I went and had a look at it today.. definately a GMC, definately not a '41-'46.
It had the headlights sticking out of the side of the radiator, like the pre-'41 trucks, but had a dash identical to what you see in a '41-'46 chevy.
Windshield was also split type, and looked just like you'd find in a '41 thru 46.
So other than the headlights being mounted off the side of the radiator, and the grill being way different, it looked just like my '46 2 ton.
From what i've seen in the gallery, it's gotta be a 1939 or 1940.. the grill this thing had is identical to the ones pictured in the '39 gallery.
The bad news is that the windshield frame is shot, the fenders are banged up, the seat is toast, and the engine is missing a carb, starter, and generator. No vac wiper motor, and the windshield crank is shot.
The good news is the chrome grill looks just about perfect.. but i'm not luggin' that thing home just to yank the grill out of it.
I ended up buying a GMC cab for $50 that looks identical to my '46 cab, except the dashboard is flat like a dodge or ford, and has round gauges.. but it's got a split windshield with a really nice frame.. maybe that one is a '39? Looks like from the gallery that '39 is when they started with the split windshield in the GMC's.