Question about A6

Im interested in buying a used A6, probably between 1998 and 2000. One of my major caveats is that I cant find any information about the GPS/Nav systems that Audi offers and Im trying to get some feedback about that specific model of those years.

Ive test driven some of the A6's that had a NAV system in it but it wasnt the NAV with the screen that you can see all the streets etc... it was a very simple NAV in the cluster that told you which direction to go. Im looking for the one with the full screen (not sure of the terminology of the 2 styles).
so heres the question;
What year did audi start putting in any type of NAV into the A6's?
What year did they start putting in the full screen as I described above into the A6's?
If I buy an A6 that has no NAV or the simpler NAV can I upgrade it to the stock full screen style?

If this is discussed in one of the forums than please direct me there but I couldnt find it.
Im sure that an aftermarket unit can be installed but I like the stock look and thats what I want to stay with.

Lastly, I couldnt find anywhere on this forum that discusses feedback on specific models. Im looking to get some info about the pro's and con's of the A6's between 98 and 00, both from professionals and from owners.
Thanks very much for your help.
Isaac
Shnerez420@aol.com

Hi Shnerez420, welcome to the forum. I saw you have posted the same question in another forum. Please do not cross post questions. I answered to your other one btw.