The fifteen Z50r 1982 (c) Usa Gasket Kit B component parts are all listed in this schematic.
A sample from the products for the Gasket Kit B include: O Ring, 107x2, Gasket,oil Pump (nas), Gasket,clutch Out (nas), O Ring, 8 Dia.
In this schematic the "O-ring,6x1.7" is used most often.