GMC 2003 Yukon Owner's Manual page 416

2. Remove the lamp assembly.
3. Press the release tab and turn the bulb socket
counterclockwise to remove it from the taillamp
housing.
5-58
1. Use a tool to remove
the two screws from
the lamp assembly.
5. Press a new bulb into the socket, insert the socket
into the taillamp housing and turn the socket
clockwise into the taillamp housing until it clicks.
6. Reinstall the rear lamp assembly.
4. Pull the old bulb
straight out from the
socket.