MK3 or MK4, CD to DVD Navi swap?

How can i tell if my navi is a MKIII or MKIV? This might be the answer to my 1st question but i have a CD Navigation unit(probabably MKIII sign) and i would like to know if its possible to swap it out to a DVD navigation and what is the process if possible?

Thank you.

The mark 3 takes up half of the upper center console, where as the mark 4 takes up all of the upper center console.

Not sure about the DVD/CD thing, maybe some other owner can chime in.

*edit* just noticed you have a 745i (E65) I thought you were talking about the last body style 7 (E36 I think). Anyways, we got upgraded to a DVD unit because our CD unit kept dying on us.

Sounds like you have the CD navi unit. If its mkIV it will have the DVD logo on the front of the unit. It is possible to upgrade. They sell upgrades on ebay you can easily install yourself (thought u will need to go to dealer for re-programing) for about $1k. Or you can mess with your CD unit until it fails, then take it to the dealer and they will upgrade you to a DVD unit under warranty.