Ford 2003 Mustang Workshop Manual page 489

53. NOTE: Tighten the bolts prior to releasing the carrier spreader.
Install the differential bearing caps in their original locations and positions and tighten the bolts.
54. Remove the special tool.
55. Install the special tool at the 12 o'clock position.
56. Using the special tools, measure the differential ring gear backlash at four equally spaced
points.