As posted/corrected above by vandutchman, the Panel Truck and Canopy Express (there was no 3806/3116 Suburban Carryall) 1/2 ton and 1 ton fuel tanks were different. The radiators were slightly different.

3105/3107 1/2-ton Panel Truck and Canopy Express fuel tank and radiator specs

3805/3807 1-ton Panel Truck and Canopy Express fuel tank and radiator specs