When I did my electric fan swap. I put a big clamp on the main pulley so it couldn't turn, then put a big wrench on the fan bolt and took it off that way.
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When I did e-fans in my TBSS, I left the belt on and put a wrench on the nut. I hit the wrench with a hammer a few times and it came loose.
I found a kit that had the pump, thermostat, and lower hose for $100 shipped. I'll be ordering it by this weekend.