For 1350 / 1410 series OEM and NASCAR type companion flanges. Kit includes two billet caps made of heat-treated alloy steel and four 5/16"-24 12-point large flange high-strength fasteners that have provisions for safety wire. For use with MW NASCAR type 39024 or 39924 pinion yokes. This kit will fit yokes that utilize 5/16"-24 threads on 1.8" centers with the joint center .030" below the face of the flange. Increases u-joint failure point by 500 foot-pounds of torque. Sold as a pair.