I'm writing this just to share my experience with this problem and hopefully help someone Problem: 96 Explorer: Speedometer slowly gets the bounce. First noticed it in higher gears shifting back and forth. After awhile the bounce gets worse, then transmission isn't sure when to shift. (Since the computer uses the speed sensor to know how fast the truck is moving) Sometimes stays in higher gear at a dead stop. Eventually, the speedometer does hardly anything and transmission has no clue what to do, pretty much undrivable, unless you shift manually and stay away from the highways. Fix: 1. Started out by changing the speed sensor. (no change) 2. Pulled speed sensor out of transfer case leaving wires attached, removed plastic gear from sensor and attached cordless drill and ran the drill while the ignition is on. (NOT STARTED) Found that the speedometer worked nice and smooth. That eliminated the console and wiring. Only 1 thing left. 3. Changed gear in the transfer case that drives the speed sensor. (Change both plastic gears right away.) Runs like a top.