Short Shaft Fan Clutch
yeah i have about the same 1/2 inch with a stock radiator on my 2947 in my 65. I bought a 18 fan but it was too big and was going to rub on my radiator at the top so i ended up buying a 17117 it fits great. Just finishing up my 340 swap so i dont have any miles on it yet but all is good at idle.