Do the Nav disks cover Alaska? If it does not, is there a disk that does have it? Will it work with GM units? I dont really need the Nav unit but would like to have the screen for the back up camera and dvd screen but I still want to use the steering wheel controls and keep the stereo plugs in the back operable. Thank you.

AFAIK it covers Alaska....I know for sure it covers Canada...

How well does the mapping cover Canada? EG, smaller towns and secondary hiways etc....

Thanks..