Let me ask a stupid question though. If it is the heater core all I would have to do is turn the heat off in order to drive it from Asheville to Charlotte correct?
If the heater valve works, then yes. If not then pull the heater line at the top of the PHH hard line (on the back of the intake) and run some heater hose over to the return on the exhaust side of the engine.
Whoever talks to this guy needs to ask, is it wet inside the cab or elsewhere?