Two problems related to differential unit have been reported for the 1998 Ford Expedition. The most recently reported issues are listed below.
Began making noise. Had it checked and repaired by dealer. Dealer said this was a "factory" defect where the ring and pinion gear were very badly mis-aligned. The Ford dealership mechanic said it was the worst he has ever seen. He said this was responsible for the pending failure. He said if we had waited, it would have caused a failure. We reported this to Ford motor company, but they said they would take no responsibility. We feel since this was a factory defect and not normal wear and tear that the company should take responsibility for this.
Rear differntial fluid covers brakes, makes braking difficult (major hazzard??).