let me start out by saying that that set up is totally a PITA. I do know the autozone tool is a joke. well first off, get some brake fluid, or if you can, some PB blaster and soak the nut. When something is super tight like that you need to bang on the place were it is bonded. with a pipe and hammer or what ever. For a while, sometimes a long while. the shock can help loosen it
What i did was I pulled the radiator and the water pump then took the pump, clutch and fan and worked on it on my bench instead of on the truck. I found a flat peice of metal and drilled holes in it and bolted it to the pulley, then took a pipe wrench to the big nut. First I tried loosing the four fan bolts so I had room for my creasant wrench to fit. Sometimes when you live in the sticks you have to make do with what you have. At worst, it would be the price of a water pump gasket,or you could rtv it back on.