I've got a non-current unlocked version of City Navigator on a PC that I have the urge to experiment with. Want to try it out on my Montana and then if I like the way it works switching between the 100k and 24k topos that I have on there, I'll buy the latest greatest City Nav and put it on there instead of the old one. My question concerns what is essential or necessary. for the City Nav to function properly and fully. I made a Garmin folder on the uSD card and copies the gigantic .img file over to it. Now, the Montana seems to display and show tracks as they are being created on the City Nav map (when enabled) but surely there must be more to it than that. There are many files and subfolders on the PC that must have importance. Any thoughts?