Chevrolet 2011 Express 1500 Cargo Owner's Manual page 311

2. The third nut (C) is under the
applique piece (B) above the
lamp. Remove the two inboard
applique nuts. Pull the
applique (B) straight rearward
slightly to clear the studs. Then
rotate the applique (B) just far
enough to gain access to the
outer push pins (A).
3. Carefully disconnect the push
pins (A) from the applique
bracket
4. Remove the third nut (C) from
the upper outboard side of
the lamp.
5. Remove the taillamp assembly
from the vehicle.
6. Remove the taillamp/turn signal
lamp (A) or back up lamp (B)
bulb socket by turning it
counterclockwise one quarter
turn and pulling it out of the
lamp assembly.
7. Remove the bulb by pulling it
straight out.
8. Push the new bulb into the
socket.
9. Reinstall the bulb socket by
turning it clockwise into the
lamp assembly.
10. Reverse Steps 1 through 5 to
reinstall the taillamp assembly
and applique.