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 WarningInstallation Procedure
Align the rear compartment floor panel.
Drill 8 mm (5/16 in) for plug welding along the edges of the rear compartment
floor panel as noted from the original panel.
Clean and prepare the attaching surfaces for
welding.
Position the rear compartment floor panel on the vehicle.
V ...
Installation Procedure
Clean and prepare the attaching surfaces for welding.
Apply structural adhesive to the attaching surfaces.
Position the body rear end panel on the vehicle.
Verify the fit of the body rear end panel.
Clamp the body rear end panel into position.
Spot weld accordingly as no ...
Instrument Panel Outer Air Outlet Duct Replacement
Preliminary Procedure
Remove instrument panel assembly. Refer to Instrument Panel Assembly
Replacement.
Instrument Panel Outer Air Outlet Duct Screw (Qty: 7)
Caution: Refer to Fastener Caution in the Preface section.
Tighten
2.5 N·m (22 lb in)
Instrument Panel Outer Air Outlet Duct
Floo ...