Sonnax offers an oversized o-ring MT-O-10V, to be used in Mitsubishi F4/R4A51, F5/R5A51 torque converters with worn piston bores. Resize the bore to 2.298" +/-.001"(58.37mm +/-0.025mm). To avoid the risk of the o-ring coming out of the groove, be sure not to exceed this recommended bore specification.