I don't think they are the same,they look the same but I think the difference is in the recessed area for the horn button,it may be bigger or have another reinforcement rib then the 37 which would work if you used the 39 horn button. I am not 100% sure on this but remember when asking the question myself on the old Fordbarn and answer I got. I looked in my 37 book and naturally I note #78 part number but do not see this # carryover to 38-39 standard,but this could be because the 38-39 standard wheel was not black but zephyr beige.