My 99 F250 with a V10 had an abs light come on and then it would go off. Now the ABS light stays on and it drove fine for a little while but the other night the Service Engine light came on along with the ABS light. Tranny was shifting harsh, winding out and I scanned the codes and got P0500.

Is it the sensor on top of the rear differential or is it the ABS light causing the problem?

 

Yep, most likely the VSS on the differential judging by both the P0500 and the harsh shifting. Is your speedometer working though?

 

Speedo was working