How to install a aftermarket radio in a 2004 GMC Sierra?

To install an aftermarket radio in a 2004 GMC Sierra, start by disconnecting the negative battery terminal to ensure safety. Remove the dashboard trim and the factory radio using the appropriate tools, such as a panel removal tool and a socket wrench. Connect the aftermarket radio to the wiring harness adapter and mount it into the dash using the provided brackets. Finally, reassemble the dashboard, reconnect the battery, and test the new radio to ensure it works properly.