On this parts fiche the Washer(10x15x1.5) is the most specified component.
Some items from this specific schematic: Tank Assy,reservoir, Hose Comp,rear Brake, Piston/cup Set, Diaphragm.
This part-list fiche shows all the components that make up the Lt230s 1986 (g) Usa (e03) Rear Master Cylinder (model F) .