Assuming you have a '37 passenger car the one you need measures 3.00 inches from the front of the blade to the rear of the hub according to the Green Bible. It is part number 78-8600 and fits '37, '38 and '39 standard. I have a couple that measure 1 5/8 from the front of the blade to the rear of the hub in case anybody needs one. I bought them by mistake while looking for one for my '37. Hold out for the correct one or the blades will hit something.
Charlie Stephens