Toyota Repair: Speedometer reading too fast., running down the road, gear changes

Question
I have a 1997 10th month of 1996 build date, Toyota Tacoma v-6 extra cab 4x4 5 speed manual. I can be running down the road at 70 mph and the speedometer reads about 110mph. The truck has 31in tires on it ,  with no gear changes I dont think . I was not the original owner. The truck has 147,000 miles and was doing this when I bought the truck.I have seen no vss on the transmission or transfer case.  Can you help?

Answer
There should be a cable that runs to the rear of the transfer. The seal in the drven gear may be leaking and sending oil up into the head.
You can take the cable off and see if its wet.
You can replace the speedo sleeve in the trans if it is.

Mike