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 WarningCalifornia Fuel Requirements
If the vehicle is certified to meet California Emissions Standards, it is designed
to operate on fuels that meet California specifications. See the underhood emission
control label. If this fuel is not available in states adopting California Emissions
Standards, the vehicle will operate satisf ...
Front End Upper Tie Bar Support Sectioning (MAG Welding)
Note: According to different corrosion warranties, only the
regional mandatory joining methods are allowed.
Removal Procedure
Warning: Refer to Approved Equipment for Collision Repair Warning in the
Preface section.
Warning: Refer to Collision Sectioning Warning in the Preface section.
W ...
Installation Procedure
Cut the roof front header panel in corresponding locations to fit the
remaining original panel. The sectioning joint should be trimmed
to allow a gap of one-and-one-half-times the metal thickness at the
sectioning joint.
Create a 50 mm (2 in) backing plate from the unused portion of ...