SuperPro KIT136SK Rear Greasable Shackle and Bushing KitSuperPro KIT136SK Rear Greasable Shackle and Bushing Kit The Shackles and Fixed Pins are often overlooked when upgrading the suspension of a 4WD. Original shackles and fixed pins corrode and destroy the bushings and it is the leaf spring bushings that stabilise the movement of the rear axle. Worn or inferior bushes in this area will cause the solid rear axle to move and impart rear end passive steer to the vehicle leading to the vehicle 'wandering'