Mercury Mariner Outboard 225 3 Litre Service Manual 1994, Page 305Get this manual
5Assemble the forward gear installation tool to the forward gear, then place it (with the forward gear, thrust bearing, and thrust race) down over the propeller shaftEnsure that the thrust race seals evenly onto the shimTap the thrust race down lightly with soft tooldo not damage the thrust race surface 6_ Instalilhe forward gear bearing adaptor using hook tool (which was fashioned when the adaptor was removed) as shownEnsure that the adaptor seats evenly against Ihe thrust race