Chevrolet Express Owner's Manual page 292

2. The third nut (3) is under the
applique piece (2) above the
lamp. Remove the two inboard
applique nuts. Pull the
applique (2) straight rearward
slightly to clear the studs. Then
rotate the applique (2) just far
enough to gain access to the
outer push pins (1).
3. Carefully disconnect the push
pins (1) from the applique
bracket.
4. Remove the third nut (3) from
the upper outboard side of
the lamp.
5. Remove the taillamp assembly
from the vehicle.
6. Remove the taillamp/turn signal
lamp (1) or back-up lamp (2)
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 5 to reinstall
the taillamp assembly and
applique.