Ken
i installed the factory Nav in an 03 and added a 6 disc changer as well.
the only wire i had to run was for the VSS from the speedo to the nav unit i also added a few adapters all of which i purchased from
http://www.jpcustoms.com you can see the post here
http://www.elcovaforums.com/forums/s...ead.php?t=3111
i replaced the onstar with an indash dvd player which will play through the nav unit also installed a back up camera. any questions let me know i will do my best to help
Jay