Destructicon· Super Moderator
Welcome aboard. It is highly unlikely that the ring inside the differential is a problem. If it is, the differential would likely require a major overhaul. The sensor on the differential is another matter. Cheap and easy to replace, it is a good starting point. Be sure to check the differential oil level while you're under there. Also, check the condition of the wiring going to the sensor. The RABS control module should be up in the dash somewhere, but, being a van body, I'm not sure where it would be. The other part of the RABS system should be near the master brake cylinder. This system should also control the speedometer and indirectly, the cruise control.