This is actually for my fathers truck, I've also seen the same fault in my father in laws which is a similar model year. Essentially one by one the gauges in the dash stop working entirely. With my fathers the speedometer arrow actually fell off of its mount and is lying at the bottom of the gauge window. The solution fo this is to remove the dash and replace every single gauge. Dad's solution was to mount a gps to the top of the steering wheel stock for speed and then hope that nothing mechanical happens cause it'll be hard to tell until you see smoke or hear knocking.