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 WarningGeneral Plastic Repair
Warning: In order to reduce the risk of personal injury when exposed
to toxic fumes while grinding, cutting, or applying repair material on
any type of sheet molded compound or RIM rigid plastic, observe the following
guidelines:
Work in a properly ventilated area
Apply protective cream t ...
Removal Procedure
Warning: Refer to Approved Equipment for Collision Repair Warning in
the Preface section.
Warning: Refer to Glass and Sheet Metal Handling Warning in the Preface
section.
Disable the SIR System. Refer to SIR Disabling and Enabling.
Disconnect the negative battery cable. Refer to Bat ...
Symptoms - Squeaks and Rattles
Table 1: Rattle Coming From the Side Rail
Table 2: Rattle Under Vehicle at Higher RPM
Table 3: Thump From Rear of Vehicle on Bumps
Table 4: Glass Knock Coming From the Rear of the Vehicle When Driving Over
Bumps
Table 5: Rattle Coming From Door
Table 6: Squeak When Operating Doors
Table 7: S ...