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 WarningVehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label
Vehicle Certification Label
The vehicle certification label is located on the driver door and displays
the following assessments:
Gross Vehicle Weight Rating (GVWR)
Gross Axle Weight Rating (GAWR), front and rear
The gross vehicle weight (GVW) is the weight of the vehicle and everything it ...
Installation Procedure
Remove all mounds or loose pieces of urethane adhesive from the
pinch-weld area.
Inspect for any of the following problems in order to help prevent
future breakage of the window:
High weld
Solder spots
Hardened sealer
Any other obstruction or irregularity in the pinch-weld fla ...
Ignition Positions (Key Access)
The ignition switch has four different positions.
Notice: Using a tool to force the key to turn in the ignition could
cause damage to the switch or break the key. Use the correct key, make sure it is
all the way in, and turn it only with your hand.
If the key cannot be turned by hand, see yo ...