The radiator is new from Summit. Yes I flushed it out and water going in one end comes out the other. The water pump has an impeller: I remember taking it off to clean it off and put a new gasket on it. I think some of the impeller had probably rust pitted away, however, if memory serves. I didn't think it was enough to matter or I would have replaced it right away.
I think I'm going to go ahead and take the water pump off and poke around the front of the engine with my copper wire. I'll see if I can talk the truck's owner into getting a new water pump. Amazon has the reman. (58-684: I think it's a Cardone #) one for $80 + free shipping (they say).
