I own a 2008 Suburban with the optional OnStar Navigation System. It works as it should. But, with the newer vehicles in the past two years using 4G I am curious as to whether anyone has had an upgrade of their system. If so, did you have to replace the hardware or is OnStar able to download the new programming into the original system that comes in the older model trucks? I know of the disc for mapping because when it gets real cold the screen flips up and disc ejects. Does anyone know if OnStar offers an updated disc for the Navigation?