How do you repair a heater core on a 1965 Buick Riviera?

To repair the heater core on a 1965 Buick Riviera, first, disconnect the battery and drain the cooling system. Then, remove the dashboard to access the heater box, which typically involves taking out screws and bolts. Once you reach the heater core, disconnect the hoses and remove it from the heater box, replacing it with a new or refurbished unit. Finally, reassemble everything, refill the cooling system, and check for leaks.