GMC 2009 Sierra - Manual (Page 315)

Service
For service and parts needs, visit your dealer/retailer.
You will receive genuine GM parts and GM-trained
and supported service people.
Genuine GM parts have one of these marks:
Accessories and Modifications
When non-dealer/non-retailer accessories are
added to your vehicle they can affect your vehicle’s
performance and safety, including such things as,
airbags, braking, stability, ride and handling, emissions
systems, aerodynamics, durability, and electronic
systems like antilock brakes, traction control and stability
control. Some of these accessories could even cause
malfunction or damage not covered by warranty.
GM Accessories are designed to complement and
function with other systems on your vehicle. Your
GM dealer/retailer can accessorize your vehicle
using genuine GM Accessories. When you go to
your GM dealer/retailer and ask for GM Accessories,
you will know that GM-trained and supported service
technicians will perform the work using genuine
GM Accessories.
Also, see Adding Equipment to Your Airbag-Equipped
Vehicle on page 1-68.
5-3