GMC Sierra 2010 Owner's Manual page 202

Rear Vision Camera Location
The image is provided by the camera located in the
bezel for the tailgate handle.
The camera uses a special lens. The distance of the
image that appears on the screen differs from the actual
distance. The area displayed by the camera is limited.
The camera does not display objects which are close
to either corner of the bumper or under the bumper.
The area displayed on the screen can vary according to
vehicle orientation or road conditions.
3-66
The following illustration shows the field of view that the
camera provides.
A. View displayed by the camera.
B. Corner of the rear bumper.