Ford 2003 Mustang Workshop Manual page 334

Setting pinion depth
7. NOTE: Apply only a light oil film on the differential pinion bearings before assembling the tools.
Assemble and position the following in the differential housing.
1. Position the Adapter for 205-S127.
2. Position the Adapter for 205-S127.
3. Position the inner pinion bearing.
4. Position the Adapter for 205-S127.
5. Position the Adapter for 205-S127.
6. Position the outer pinion bearing.
7. Thread on the Adapter for 205-S127.
8. NOTE: This step duplicates final differential pinion bearing preload.
Using a Nm (inch/pound) torque wrench, tighten the special tool to specification.