Hi,
Did you check if the stop light fuse (Fuse G - 20A) in the fuse block is OK you didn't say?
If the fuse is OK, here's the stop light wiring diagram from the 1998-2000 Durango service manual that shows the wiring for the stop lights.
[image|2692802]
(click on image to enlarge)
Regarding the gears, check if the gearshift cable is OK. Here's the adjustment procedure.
[image|2692812]
(click on image to enlarge)