With our new gears ready to install, we started with the pinion gear. Oftentimes, you can install gears without a pinion depth tool by starting off with the shim that the rear originally had. Ford Racing gearsets usually line right up by using the stock shim. Non-OEM gearsets (like the Pro 5.0 gears here) like to go in with no shim at all. Like all 8.8 Fords, a crush collar is used to set pinion bearing preload and with the pinion nut tightened slowly by an impact gun. We looked for a resistance that was snug to turn by hand (about 20 lb/in for new bearings, 12 lb/in for used bearings).