1996-2005 Suzuki DF40, DF50 Four Stroke Outboard Service Manual, Page 279Get this manual
LOWER UNIT 9-26 CHECKING DRIVESHAFT THRUST PLAY After obtaining optimum tooth contact, driveshaft thrust play should be measured1Affix gear adjusting gauge to driveshaft09951-09530Gear adjusting gauge 2Slowly push driveshaft downwardRead the maximum playDesignate this amount of play as (A)
NOTE: Driveshaft thrust play (A) must be known to adjust reverse gear shimRECHECKING DRIVESHAFT THRUST PLAYReverse gear back-up shim adjustment1After adjusting forward gear tooth contact pattern, correctly assemble propeller shaft, housing assembly, reverse gear and related components (see page 9-17 to 9-18)