The Sierra 18-2631 Lower Unit Seal Kit is interchangeable with the following: Chrysler/Force/US Marine FK1061. Contains: (2) 18-2945 Drain Screw Gasket, (1) 18-7127 O-Ring, (1) 18-0500 Oil Seal, (1) 18-0512 Oil, (1) 18-7166.