How do you replace the heater core in a 1998 buick regal?

To replace the heater core in a 1998 Buick Regal, start by disconnecting the negative battery cable and draining the coolant from the radiator. Remove the dashboard, which involves taking out screws and disconnecting electrical connectors to access the heater core. Detach the heater core hoses from the engine compartment, remove the old core, and install the new one. Finally, reassemble the dashboard, reconnect the hoses, refill the coolant, and reconnect the battery.