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
Cut the front hinge pillar body 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 ...
Installation Procedure
Create 8 x 14 mm (5/16 x 15/16 in) slots for MIG-Brazing along the edges
of the drivetrain and front suspension frame front support
as noted from the original panel.
Clean and prepare the attaching surfaces for brazing.
Position the drivetrain and front suspension frame ...
Transmission Messages
SERVICE TRANSMISSION
This message displays if there is a problem with the transmission. See your dealer.
TRANSMISSION HOT — IDLE ENGINE
This message displays and a chime sounds if the transmission fluid in the vehicle
gets hot. Driving with the transmission fluid temperature high can cause dama ...