I had a wierd breakdown with my S-10 this afternoon. The fan hub on the waterpump shaft came off. That let the fan and fan clutch go wild, shattering the shroud and finally sinking about 3" of fan blade in the bottom of the radiator. Wasn't making any revs, putzing along about 35, I wonder what it would have been like if I had been under full throttle getting truck and trailer up to speed in traffic. Probaby the resulting "crunch" would have been a LOT louder. I'm thinking the shaft and hub are furnace brazed during assembly but the shaft looks like it has red loctite on it whre the hub fit. I have a spare radiator and shroud, I'll put on a new waterpump and keep my spare for some middle of the storm in the middle of the night breakdown. It could have been a lot worse, if it hadn't stuck in the radiator it could have danced around until it took out coolant and AC hoses.