1996-2005 Suzuki DF40, DF50 Four Stroke Outboard Service Manual, Page 280Get this manual
9-27 LOWER UNIT CHECKING PROPELLER SHAFT THRUST PLAY After adjusting all gear positions, measure the propeller shaft thrust playif not within the following specification, shim adjustment is requiredPropeller shaft thrust play0.20 0.40 mm (0.008 0.016 in