Mack Hexagon Screw 25091811, 1AX509 (Pack of 4)

Heavy-Duty Torque Rod Bolt / Hexagon Screw 25091811 (also cross-referenced with legacy part number 1AX509) is a high-tensile structural fastener engineered for commercial truck suspension and chassis applications. 

It is used to secure high-stress structural components—such as suspension torque rods, brackets, and heavy framework assemblies—where continuous articulation, heavy load shifts, and high torque loads are present. Precision-manufactured from high-strength steel, it resists stretching, shearing, and fatigue under severe vocational and highway operating conditions.