Looking at a Traverse with the rear dvd.
is it possible to upgrade the headunit to, say, an aftermarket Pioneer AVIC or Eclipse AVN and still be able to use that rear DVD?
Don't know if you are still looking for this info, but the Metra GMOS-100 (Axxess part actually) is a very nice unit for installing aftermarket in the 2009-2011 Traverse. It provides all wire hook ups to install aftermarket radio, plus rear seat entertainment integration harnesses. It also retains OnStar perfectly, and blinker/chime without making a real mess of the system. I just installed a Kenwood nav unit in our 2011 and love it. It is pricy but well worth the $$$. There is plenty of room in the center console right under the head unit to stash the 3.7 million wires (exaggeration)
Let me know if you have any more questions.