Master Parts Book says they are the same, either side. But MUST be from following GMC models or their Chevy equivalents:
150, 250, 280 EC & FC (3/4 to 1 1/4 ton 1947-50)
300 AC, CC, EC & FC (1 1/2 ton 1939-50)
150-22 & 250-22 (3/4 or 1 ton 1951-52, Part was stamped 3681155)
As you know, the 3/4 and 1 ton have eight lug wheels.