Leak over muffler at right rear on 2004 Chevrolet Trailblazer

DEX COOL leaking from right rear quarter panel. It smells like anti freeze, and I am adding new coolant to the radiator. Does the trailblazer have a rear heater core?
How much should I expect to pay to get a rear heater core replaced?

Does it have rear A/C? If yes then it does have a rear heater core.