GMC Sierra 2000 Owner's Manual page 314

Front Turn Signal Lamps
(Composite Headlamps)
2. Squeeze the tab on the side of the lamp socket while
turning the socket counterclockwise.
6-42
1. Remove the four
screws and take out the
parking/turn signal
lamp assembly.
4. Push in gently on the bulb, turn it counterclockwise
and remove it from the socket.
5. Put the new bulb into the socket, gently press in on
the bulb and turn it clockwise until it is tight.
6. Put the socket back into the lamp assembly and turn
it clockwise until it locks.
7. Put the parking/turn signal lamp assembly back into
the vehicle and tighten the four screws.
3. Pull the socket out of
the lamp assembly.