That is a 2-ton truck, similar to a 6000 series in Chevy's. It is built with heavier components than the Chev in the springs, mounts and engine areas at least. The first three #'s are your engine size, a 270 in this case. The radiators are diff and heavier in GMC's too. Is your rear a one-line vacumm switch or electric? You probably have six-lug wheels and not 10-lug like Chevs? 20" tires? Your drivers door frame may have the plate with model and info about HP of engine, GVW and such. OR, maybe in glove box door. Shop manuals for GMC are available and go up to the 400 series in them. Get one if doing repairs, lots better than Chev books. :p
