Check out any of the twenty-one Seat (model S/t) components enlisted.
The Dr650rse 1994 (r) (e04 E18 E21 E22 E34 E53) Seat (model S/t) consists of twenty-one pieces with the Seat Set being the most expensive.
Some items from this specific schematic: Seat Set, Cushion,upr, Screw, Cushion,lwr.