This is where I got confused when I asked for part numbers. The VSS or vehicle speed sensor is thrown around to, many different sensors.
For 1996, the vehicles speedometer sensor is on the transfer case right above the rear drive shaft speed sensor both have been called VSS from my readings. The front drive shaft sensor in the transfer case under the clutch motor, which also, has been called VSS.
You also have a sensor in the rear differential that is for antilock brakes that has been called a VSS.
If you have problems with speedometor then the sensor on top of transfer case where the rear driveshaft comes out might be something to look into.
If you have your 4wd kicks in but flashes 6x after hitting above 40mph for a minute and you have very limited front wheel drive power then the sensor below the speedometer where the rear drive shaft comes out might be your problem. This sensor tells the computer that the rear wheels are spinning faster then the front and applies more pressure to the clutch that applies power to front wheels. The default mode is minimum power to front wheels.
In default mode the rear wheels and front are spinning at the same rate. If the rear tires starts spinning but the computer doesn't see it because of faulty or dirty sensor then its not going to engage the clutch to put more power to front wheels.
It you can go into 4wd (auto) and you are always 100% locked on the front. You will notice it turning on dry payment. Then your front drive shift sensor is to be looked into. Its telling the computer that the front driveshaft is not spinning. If the the computer sees the rears spins but not the front then it puts max power to front wheels all the time.
If you have both rear and front driveshaft speed sensors go out, I can only assume instant self destruction.
