2001 Mercury Mariner 50-60HP Factory Service Manual, Page 504Get this manual
BIGFOOT GEAR HOUSING
10Install locating disc against bearing carrier shoulder in gear housing11Position access hole as shown
a -Locating Disc -Access Hole 12Determine pinion gear depth by inserting feeler gauge thru access hole in locating disc13The correct clearance between gauging block and pinion gear is 0.025 in(0.64 mm)14If clearance is correct, leave Bearing Preload Tool on drive shaft and proceed to "Determining Forward Gear Backlash," following15If clearance is more than 0.025in(.064mm) add shims behind the bearing raceIf clearance is less than 0.025in(.064mm) remove shims from behind the bearing raceWhen reinstalling pinion nut, apply Loctite 271 on threads of nut