How do you change the heater core of a 1977 nova?

To change the heater core of a 1977 Nova, start by disconnecting the battery and draining the coolant from the radiator. Remove the dashboard and any necessary components to access the heater box, then detach the heater core from its housing. Install the new heater core, reassemble the heater box and dashboard, and refill the cooling system with coolant before reconnecting the battery. Finally, check for leaks and ensure the heating system functions properly.