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:

California Proposition 65 WarningSteering Linkage Outer Tie Rod Inspection
Special Tools
GE-8001 Dial Indicator Set
For equivalent regional tools, refer to Special Tools.
Note: This inspection procedure does not supersede local government
required inspections that have more stringent requirements.
Inspect the outer tie rod seal. If the outer tie rod ...
Crankshaft Position System Variation Learn
Note: The crankshaft position sensor system variation learn procedure
is required when the following service procedures have been performed, regardless
of whether DTC P0315 is set:
Engine replacement
Engine control module (ECM) replacement
Crankshaft damper replacement
...
Inspection/Maintenance Complete System Set Procedure
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
Review Strategy Based Diagnosis for an
overview of the diagnostic approach.
Diagnostic Procedure Instructions provides
an overview of each diagnostic cat ...