Ford 2003 Mustang Workshop Manual page 440

8. Using the special tool, remove the rear axle pinion flange.
Installation
1. Inspect the rear axle pinion flange seal journal for rust, nicks, and scratches prior to installing
the flange. Polish the seal journal with fine crocus cloth, if necessary.
2. Lubricate the rear axle pinion flange splines.
Use SAE 75W-140 High Performance Rear Axle Lubricant F1TZ-19580-B or equivalent
meeting Ford specification WSL-M2C192-A.
3. NOTE: Disregard the index marks if installing a new rear axle pinion flange.
Position the rear axle pinion flange.
4. Using the special tools, install the rear axle pinion flange.