Replaced all the radiator and heater hoses today.

As an aside, when I got the truck, it had a short piece of hose recirculating the heater circuit, so I assumed the heater core was bad. As part of the heater restoration, I took the core to a shop to get it cleaned and repaired... they said it tested good... don't know why the heater was disconnected.

I also suspected the thermostat was stuck open... discovered today it didn't have one (same effect, of course). Need a radiator cap, now. Up next... temp gauge test!