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 WarningRemoval Procedure
Warning: Refer to Approved Equipment for Collision Repair Warning in the
Preface section.
Warning: Refer to Collision Sectioning 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 Dis ...
Installation Procedure
Install the following components on the drivetrain and front suspension
frame if removed:
The radiator support brackets.
The stabilizer shaft--Refer to Stabilizer Shaft Replacement.
The lower control arms--Refer to Lower Control Arm Replacement.
The steering gear--Refer to Steering ...
Trademarks and License Agreements
Manufactured under license under U.S. Patent #'s: 5,451,942; 5,956,674; 5,974,380;
5,978,762; 6,487,535 & other U.S. and worldwide patents issued & pending. DTS and
the Symbol are registered trademarks and DTS Digital Surround and the DTS logos
are trademarks of DTS Inc. All Righ ...