Of all the components that make up this Oil Pump - Primary Drive the O-ring,15.3x3.5 has the lowest price.
Parts such as the Oil Pump - Primary Drive: O Ring, 14m/m, Bolt Flange 6x14, Washer Setting, Dowel,pin,8x14 are included in the Cx500t Turbo 1982 (c) Australia Oil Pump - Primary Drive parts fiche.
This OIL PUMP - PRIMARY DRIVE assembly utilises two Pin, Knock, 3x5.2(s) - the highest specified component.