SEI MARINE PRODUCTS- Mercury Mariner Impeller Kit 47-89980T1 3.9 4 4.5 7.5 9.8 HP 1975-1986 with .438 O.D. shaft. This impeller kit replaces OE#: 47-89980T1 and fits 3.9-9.8 HP Mercury and Mariner outboard lower units with a .438 O.D. shaft.