F250 gas superduty speedometer jumps

No speedometer cable on this vehicle. The vehicle speed signal is sent through the anti-lock brake system module and to the speedometer in the instrument cluster. This signal comes from the rear wheels ABS sensor. It is likely that the sensor has failed or a wiring connector to the sensor is compromised. Testing will confirm this information, with use of a diagnostic tool capable of reading chassis components. So, yes, your ABS light and the speedometer concern are quite likely related.