Thought that the single port faced down and fitted to the single line from the bottom of the radiator and that the double side faced up to the 2 lines coming from the engine block...

 

I drove the truck 400+ miles on a trip last week.. No problems at all and the heater was blasting hot air all the way up till Friday night then it all seemed to crap out on me. So I am assuming that it was installed and functioning and for some reason has seized up. Also, I am running straight water because I am not going to pay $8 for gallons of coolant to blow it all down the street and driveway so my dog can lick it up. Staright water is not the culprit here I am sure.