How do you replace the heater core in a 1994 Ford Thunderbird?

To replace the heater core in a 1994 Ford Thunderbird, start by disconnecting the negative battery cable and draining the coolant from the radiator. Remove the dashboard and the center console to access the heater core, which is located behind the firewall. Disconnect the hoses and mounting screws, then carefully remove the old heater core and install the new one. Reassemble the dashboard and console, refill the coolant, and test for leaks before starting the engine.