This ball joint connects the front axle steering knuckle to the tie rod or drag link, transmitting steering input from the gearbox to the wheel assembly. It sits at the outer end of the steering linkage, where it accommodates both rotational and angular movement as the wheels turn and the suspension articulates. Wear in the ball-and-socket interface produces free play that manifests as wandering steering and uneven tire wear. The original part is machined to the same taper and thread dimensions as the host steering arm, so the joint seats fully without shimming or adapter sleeves. On installation, torque the castle nut to specification and install a new cotter pin.