eight components are shown in this Pr440 1976 Seat exploded diagram.
Parts such as the Seat: Tool Kit, Washer, Plate (838-77728-00), Double Seat Asy (8a1-24730-00), Cover, Double Seat are included in the Pr440 1976 Seat parts fiche.
On this parts fiche the Nut (2h1) is the most specified component.