How do you replace heater core on a 95 gmc sonoma?

To replace the heater core on a 1995 GMC Sonoma, first, disconnect the negative battery cable and drain the cooling system. Remove the dashboard and center console to access the heater core housing. Disconnect the heater hoses from the core, unbolt the housing, and replace the old heater core with a new one. Reassemble everything in reverse order, refill the cooling system, and check for leaks.