on a 40-41 ford the fan is bolted to the crank pulley w/4 bolts ,it is not belt driven,you should only have a single groove pully on crank? what are the numbers on the heads of this engine ?
The earlier passenger cars mounted the fan on the generator. I don't know when the trucks changed over. You might try posting your question on earlyfordv8.org.
Charlie the 39 P/U had the fan mounted on the generator as well as the 39 standard. The 39 deluxe car and 40 cars and P/U had the crankshaft mount. G.M.