Ford 2003 Mustang Workshop Manual page 392

19. Lubricate the pinion flange splines.
Use SAE 75W-140 High Performance Rear Axle Lubricant F1TZ-19580-B or equivalent
meeting Ford specification WSL-M2C192-A.
20. NOTE: Disregard the index marks if installing a new pinion flange.
Position the pinion flange.
21. Using the special tools, install the pinion flange.
22. CAUTION: Do not under any circumstance loosen the nut to reduce preload. If it is
necessary to reduce preload, install a new collapsible spacer and nut.
CAUTION: Remove the special tool while taking readings with the Nm (inch-pound)
torque wrench.
Tighten the nut to set the preload.
Rotate the drive pinion occasionally to make sure the differential pinion bearings seat
correctly. Take frequent differential pinion bearing torque preload readings by rotating the
drive pinion with a Nm (inch-pound) torque wrench.