Mercury Mariner 200, 225 Optimax Outboards Service Manual, 90-855348, Page 465Get this manual
3Assemble the thrust collar with its STEPPED SIDE DOWN toward the small thrust bearinga
aThrust CollarKeepers
aThrust CollarSmall Thrust Bearing
5Install the second thrust collar with its STEPPED SIDE UP
4Pull up slightly on the propeller shaft to gain access to the groove on the shaft for the keepersAssemble the two keepers into the groove and lower the propeller shaft