The Oring 183 is the lowest priced item on this Gasket Kit B schematic.
With two applications this O-ring,6x1.7 is the most specified part.
Parts such as the Gasket Kit B: Gasket Kit B (nas), Gskt,ck/c, Gasket,crank Case (nas), Gskt,clutch Out (nas) are included in the Z50r 1991 (m) Usa Gasket Kit B parts fiche.