I photographed these GMC M211 trucks at Arlington, Sequim and the Warhawk Air Museum in Nampa, Idaho.
Apparently, one of the visual cues between the M211 and the similar M135 trucks is the straight floor to the M211 (the M135 has boxed fender sections for the larger rear tires)
GMC M211 Truck
I find it odd that this truck only has one rear axle… shall continue to investigate