[66sprint6]

Our '67 LeMans came with no hoses going to the heater core. The engine had been replaced and the heat and AC had not been reconnected. I don't know if it was laziness or if it was because the heater core was leaking. I don't see any obvious signs of a leak, but who knows how long it's been since water flowed through it. I want to test it in the car. If it's OK I want to hook it up, because my son drives it daily, and it's starting to cool off here.
What can I rig up to check it? Air pressure? Vacuum? I don't have a lot of equipment but don't mind purchasing something inexpensive if it will tell me what I need to know.