I was going to say perhaps it was originally a platform or stake bed which had the short running boards ending at the rear of the cab but according to my 1948 Restoration Guide, at least, Chevy didn't offer those for 1/2-ton trucks.
1948 3/4-Ton 5-Window Flatbed Chevrolet 34 Years. Now with a '61 261, 848 head, Rochester Monojet carb, SM420 4-speed, 4.10 rear, dual reservoir MC, Bendix up front, 235/85R16 tires, 12-volt w/alternator, electric wipers and a modern radio in the glove box.
