The twenty-one Z550g1 Gt550 1983 Europe Uk Fr Fg It Sd Seat component parts are all listed in this schematic.
A sample from the products for the Seat include: Grip,carrier,f.black, Seat-assy,dual, Plug, Carrier,f.black/black.
Of all the components used in this assembly the Seat-assy,dual is the most expensive.