Caterpillar-style premium aftermarket track-shoe bolt. Part reference 6T1139. Size/application: Track Bolt D10N. Corresponding track nut reference: 5P8221. High-strength undercarriage fastener for the specified track-shoe assembly. Brand compatibility: Caterpillar and premium aftermarket systems built to the matching Caterpillar specification. Match thread, shank length and machine model before installation.