The backup lines are part of the Software, not the camera, so even if you replace the camera, it will not give you the backup lines. I believe 2011 or 2012 to 2014 did not get the backup guide lines, as GM changed the supplier for the radio during that time. They returned in 2015. This was a deciding factor when I chose my 2015 over a similar 2014.
As another user mentioned, you may be able to upgrade to the newer radio, but it may require dealer programming, and is currently uncharted territory.