How to change1972 Lincoln mark iv heater core?

To change the heater core in a 1972 Lincoln Mark IV, start by disconnecting the battery and draining the cooling system. Remove the dashboard components to access the heater box, then disconnect the heater hoses from the core. Unbolt the heater core from the housing, replace it with the new unit, and reassemble everything in reverse order, ensuring all connections are secure before refilling the cooling system and reconnecting the battery.