SEI MARINE PRODUCTS- Mercury Mariner Force Prop Service Kit 11-31990A 2 40 50 60 70 75 HP 2 4 Stroke This prop service kit replaces OE#: 11-31990A 2, fits 40-75 HP 2 stroke and 4 stroke Mercury, Mariner & Force outboard lower units from 1991-current. It includes the thrust washer.