How do you change third brake light on a 2005 Chevy Avalanche?

To change the third brake light on a 2005 Chevy Avalanche, first, open the tailgate and locate the two access panels on the rear of the cab. Remove the screws or clips securing the panels and gently pull them away to expose the light assembly. Disconnect the wiring harness from the old light, remove it, and then replace it with a new third brake light. Reconnect the wiring, secure the assembly back in place, and reattach the access panels.