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 WarningVehicle, Engine and Transmission ID and VIN Location, Derivative and Usage Automatic Transmission Unit
Vehicle, Engine and Transmission ID and VIN Location, Derivative and UsagePositionDefinitionCharacterDescription Vehicle Identification Number (VIN) SystemThe VIN plate-(1) is the legal identifier of the vehicle. The VIN plate is locatedon the upper left corner of the instrument panel and can be see ...