How do you replace the heater core in a 1955 Cadillac Fleetwood?

To replace the heater core in a 1955 Cadillac Fleetwood, first, disconnect the battery and drain the coolant from the radiator. Remove the dashboard and heater assembly to access the heater core, which typically involves unscrewing several screws and possibly removing the glove compartment. Once exposed, disconnect the hoses attached to the heater core and remove it from the housing. Install the new heater core by reversing the disassembly steps, ensuring all connections are secure before reassembling the dashboard and refilling the coolant.