How do you replace a heater core in a 1989 dodge B250?

To replace the heater core in a 1989 Dodge B250, start by disconnecting the battery and draining the cooling system. Remove the dashboard components to access the heater box, which typically involves taking out screws and clips. Once you have access to the heater core, disconnect the inlet and outlet hoses, unbolt the heater core from the housing, and replace it with the new unit. Reassemble everything in reverse order, refill the cooling system, and check for leaks before reconnecting the battery.