The photo in my first post is where the valve was located prior to restoration. I have no reason to believe it was not the original location as this was a very original and complete truck.
Tiny, the cooling system diagram you linked to shows the water flowing from the radiator to the water pump, i.e. inlet/suction. After it flows through the engine it exits at the thermostat, i.e. pressure side. (the actual pressure side of the pump is the outlet mated to the block)
Last edited by FallenHerosDad; 03/02/2012 11:24 PM.