Seeing the Model A rear bumper brackets, I would say they are a pile of used stock A crankshafts. I don’t see any with B style counterweights or any that have been modified. You should be able to measure the main bearing journals with a tape measure and determine what they are. The B will be 1.998/1.999 or almost 2 inches. The A will be 1.625. You should be able to visually see that difference even if you don’t have a micrometer.