Ok, I turned the air blue with all my wailing and gnashing but I finally got the first hydro pump off the donor and it is sitting on my workbench. The part that gave me all the trouble is removing from the bottom of the mower what SCAG calls
12 482085 Hub, Tapered, 15mm Bore
It is number 12 in the attached diagram. Since I have another to do I am asking if there are any tricks to this. I know about removing the screws and using them in the other holes so the screws force the hub off. This worked until the hub was almost completely off then it seemed to get stuck and the threads on the screw stripped. Since the screws were just spinning freely at that point they could not exert any pressure so that method was just not going to work. I ended up using a chisel to widen the slot in the side of the hub and with a little more cussing finally got it off. I am replacing the screws and the hub because I have no confidence in them after I saw the screws stripped. What did I do wrong? Also how do you hold the pulley while you try to get the hub off? I must be missing something!