For service and parts needs, visit your dealer. You will receive genuine GM parts and GM-trained and supported service people.
Genuine GM parts have one of these marks:

Vehicle Care
California Proposition 65 WarningSteering Gear Replacement (Hydraulic Power Steering)
Special Tools
EN 45059 Torque Angle Sensor Kit
For equivalent regional tools, refer to Special Tools.
Removal Procedure
Turn the front wheels to the straight forward position and secure the
steering wheel from moving.
Remove the lower steering intermediate shaft bolt (1).
...
Wheel Alignment Measurement
Steering and vibration complaints are not always the result of improper
alignment. One possible cause is wheel and tire imbalance.
Another possibility is tire lead due to worn or improperly manufactured tires.
Lead/pull is defined as follows: At a constant highway speed
on a typical straight ...
Taillamps, Turn Signal, Sidemarker, Stoplamps, and Back-Up Lamps
Trunk Deck Inboard Taillamps
1. Open the trunk.
2. Remove the trunk deck trim cover (1).
3. Remove the bulb socket (2) by turning counterclockwise and pulling straight out.
4. Remove the bulb from the socket.
5. Install the new bulb in the bulb socket.
6. Install the bulb socket by turni ...