GMC 2009 Sierra 1500 Crew Cab Owner's Manual page 474

Dually Models
A. Stoplamp/Taillamp/Turn Signal Lamp
B. Back-up Lamp
C. Stoplamp/Taillamp/Turn Signal Lamp
4. Press the tab, if the vehicle has one, and turn the
bulb socket counterclockwise to remove it from the
taillamp assembly.
5-64
All Other Models
A. Stoplamp/Taillamp/Turn Signal Lamp
B. Stoplamp/Taillamp/Turn Signal Lamp
C. Back-up Lamp
D. Sidemarker Lamp
5. Pull the old bulb straight out from the socket.
6. Press a new bulb into the socket and turn the socket
clockwise into the taillamp assembly.
7. Reinstall the taillamp assembly.