Models with AdvanceTrack have a enable/disable button opposite the message center buttons. To the right of the cup-holders. I'm not sure what year they started to have AdvanceTrak but I think it's '05.
To change between AWD and Locked (4WD) you have to use the message center buttons. Again, I'm not sure what year they added this feature. Maybe '04. ( I think you just have to hit the setup button until the option says AUTO or LOCKED, the the reset button to toggle between the two options.) The engaging and dis-engaging is seamless and smooth. I can barely tell what mode it's in until you go to make turns and the 4WD LOCKED reveals itself by a steering wheel that doesn't obey (as the nature of 4WD).