Mercury Optimax Models 135, 150, Direct Fuel Injection., Page 390Get this manual
RIGHT HAND NON-RATCHETING
7Position dial indicator pointer on line marked "1" on Backlash Indicator Tool, if gear ratio is 1.87:1 (15 teeth on pinion gear), or on line marked "2" on Backlash Indicator Tool, if gear ratio is 2:1 (14 teeth on pinion gear) or on line marked "4" if gear ratio is 2.3:1 (13 teeth on pinion gear)