[DD931]

I've been advertising what I thought to be an 81A- style generator pulley - has fan mounting screw holes - 4 3/8" OD. However, one gentleman asked about the inside diameter and when I told him it was 0.585 inches he said it must be for a '36 because the '38/'39 pulley had a larger ID. The Green Book shows the 68- part was replaced by the 81A- one. This is true for both pulley and generator. So, my question is: Did the original 68- generator have a different shaft diameter than the 81A- version? There is no part number on this part. Kube - is this in your area of expertise?