Yes all the seals and insulation ect will be dry rotted and prob find leaves and debri in there. On my '69 HVAC box all the original vacuum actuators still work and my original evaporator pressured tested to 100 psi was still good. So didn't cost much to put a new seal kit and heater core in there just a bunch of labor. If you wanna go that route I can find a youtube video of a guy restoring HVAC box on '69 Dart 4 door....