How do you replace a 95 Buick Roadmaster limited edition heater core?

To replace the heater core in a 1995 Buick Roadmaster Limited Edition, first, disconnect the battery and drain the coolant from the radiator. Then, remove the dashboard and the associated components to access the heater core located behind the firewall. Detach the hoses connected to the heater core, remove the mounting screws, and extract the old core. Install the new heater core by reversing the disassembly steps, reconnect the hoses, reassemble the dashboard, and refill the coolant before testing the system.