Re: Transmission on 1996 f250
The problem could be the speed sensor, the PSOM module, or the speedometer itself. I recommend replacing all of those. That way you're likely to replace the actual problem part.
I got sassy because you asked the identical question I answered above. Did you think you'd get a different answer?
Former Ford Automatic Transmission Engineer
“The good thing about science is that it's true whether or not you believe in it.” ― Neil deGrasse Tyson