Pinion Depth

Assemble depth gauge tool (T79P-4020-A) and install aligning adapter, gauge disc (.894" thick for 7 1/2" ring gear; 0.254" thick for 8 1/2" ring gear) and gauge block screw. Place rear pinion bearing over aligning disc and into bearing cup of carrier housing. Install front pinion bearing into front bearing cup. Place tool handle onto screw and hand tighten. See Fig 1.
Center gauge tube in differential bearing bore. Install and tighten bearing caps. Bearing caps must be installed in original positions. Using a feeler gauge, select thickest blade that will enter between (slight drag) gauge block and gauge tube. Insert feeler gauge directly along gauge block. When fit is correct, check thickness of blade used; this is required shim thickness (if pinion has no variations stamped on it). Remove tools and bearings.
NOTE: Gauge block must be 45° off centerline of gauge tube.

Fig 1: Sectional View Showing Installation of Pinion Depth Measuring Tools
Courtesy of FORD MOTOR CO.