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 ...
Collision Repair
Specifications
Point-to-point measurements are for reference only. All measurements are
given in millimeters. Use these measurements for diagnosing
and estimating. Point-to-point measurements are duplicated with tram bar
pointers set at equal lengths. All die marks, holes, slots, and
fast ...
Installation Procedure
Position the front end upper tie bar (1) on the vehicle.
Verify the fit of the front end upper tie bar.
Clamp the front end upper tie bar into position.
Braze accordingly.
Braze accordingly.
Grind down weld seams as needed for related panels and components.
Clean a ...