After successful years of research and development, ARB has released their most technically advanced lower yet - the competition edition 40-spline Ford 9” Air Locker. This unit has been specifically designed around the requirements of top-flight ULTRA4 racing. Each technical advancement addresses a specific concern from teams competing in the world’s toughest 4x4 events and is a direct result of testing within these same races. Among the many new design features is an integrated ring gear bolt locking system engineered to prevent the backing out of Ford 9” ring gear bolts. Fully reusable and able to resist the high torque loads applied to bolt removal, the locking tabs are designed for disassembly and reassembly for fast pit work on ring gear swaps compared to all other bolt locking systems. Key to the design is the ability to oppose the adverse effects of axle shaft eccentricity caused by typical steering joints, thereby overcoming a common problem with front applications where the differential is offset too far toward one wheel. Achieving new levels of load, wear, and impact resistance, the case is 290% stronger overall compared to standard lockers. Designed with deeper locking engagement, the competition unit ensures locking functionality is retained even after sustaining significant clutch gear tooth damage from locking under throttle. Engineered with improved internal lubrication, this unit also caters to the use of load bolts.