GMC 1998 Savana Van Owner's Manual page 274

Composite Headlamps
1. Open the hood.
2. Locate the rear side
of each
of the headlamps.
3. Without removing the headlamp assembly itself,
remove the bulb assembly from the back of the
headlamp on the driver's side by turning the bulb
to the left one quarter of a turn.
4. On the passenger's side, turn the bulb to the right
one quarter of a turn. Also, to remove the bulb on the
passenger's side, you will need to move the battery.
5.
Install a new bulb. Do not handle the glass part
of the bulb.
6 . Reverse the previous steps to reinstall the headlamp.