[gordon]

That's the 1940 version of the GMC 6 x 6, which is normally referred to as a 3 ton - no idea where they get 2 1/4 from but the rating for the later truck was 5 ton on road and 2.5 ton off road I believe.

They did use that truck to haul artillery, but it was the very length of it that made hauling such a pain, which is why the artillery prime mover version of the later production CCKW was the short wheelbase like the truck in the film - noticeably shorter than the long wheelbase truck in the image.

The badge thing was just metal utilisation. GMC badges were made of metal and secured with a couple of bolts, so they could be done away with to save metal. CHEVROLET stamped their name in the hood side panels, so no extra metal, nothing to save = the CHEVROLET name stayed on all the trucks after the revision.

I believe that early GMC had slightly different axle setups - not sure what, and also the engine displacement was lower than the 270 cu in i n the standardised truck.