D1 and D2 are the same unit... Just the D2 is a year newer and came with a different set of disks that updates on them... So if you get a new set of disks your D1 now becomes a D2.
D1 and D2 both hold a DVD Nav disk and have a slot for CD's - The down fall to the D1 and D2 is that it does not play Movies on DVD in the actual unit, you would need to get a DVD Changer to play Movies. Plus they do not have Blue Tooth abilities.
The D3 is this past years Model. - Single Disk bay. But it will play DVD Movies in the bay. Has Blue Tooth and a very good Ipod interface.
Biggest draw back to the D3 is that you have to have the NAV Disk in the drive... Plus the NAV disk holds other info like XM and Sirus Channel logo's so once you take it out of the drive you lose the logos.
The D3 will allow you to set a course and then take the disk out... But if you need to change the course you have to put the disk back in.. D1 and D2 you can change your route on the fly.
All 3 units have By-Passes to allow you to drive and change Nav location..
Cheers
Whit
