Okay, this is going back a few years. I have a 93 and it still has a speedo cable. Check under the dash to see if there is a cable screwing on to the rear of the speedo. If there is, remove it and check to see if the cable itself will spin freely with your fingers. Also, drive the truck to see if the inside cable spins. If it spins freely by hand or doesn't spin when moving, then either the cable is broken or like you said the drive gear in the tail housing of the trans.
All newer cars have a speed sensor that is electric and tells the computer how fast you are going (without a cable). My mind was working on that concept. I believe Chrysler didn't start them until 97. (And I wondering why I'm losing my hair)
Let me know.
Monday, April 5th, 2010 AT 10:10 PM