Caterpillar-style premium aftermarket track-shoe bolt. Part reference 4K7038. Size/application: Bolt 9/16-18×42. Corresponding track nut reference: 7K2017. 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.