[namba209]

Personaly, would not put the valve in the hose to the water pump, that hose pulls the coolant through the heater core, so the valve IMHO should go in the source line rather than return line. As for which tube to put each hose to, it's hard to tell by looking at the core. I would suggest a piece of hose hooked to one tube above the core, pour about a quart of water in the hose and see if it comes out the other tube. If it does, the tube with the hose goes to the top of the core and that's where I would put the flow control valve. HTH.