Ford 2003 Mustang Workshop Manual page 282

2. Use a box wrench on the ring gear bolts as a lever to rotate the ring gear several complete
revolutions in both directions or until a clear tooth contact pattern is obtained.
3. Certain types of gear tooth contact patterns on the ring gear indicate incorrect adjustment.
Incorrect adjustment can be corrected by readjusting the ring gear or the pinion.
Contact Pattern Location
In general, desirable ring gear tooth patterns must have the following characteristics:
drive pattern on the drive side ring gear well centered on the tooth
coast pattern on the coast side ring gear well centered on the tooth
clearance between the pattern and the top of the tooth
no hard lines where the pressure is high
Acceptable ring gear tooth patterns for all axles.
Correct backlash with a thinner pinion position shim required.
Correct backlash with a thicker pinion position shim required.