Much of the jarring ride of the 3500 rear can be attributed to the factory vulcanized bushings in the leaf spring pack and shackle. The factory shackle is very strong BUT the design is not conducive to a smooth ride. The Carli shackle is constructed of 1/4″ American cold-rolled steel. The mid-length gusset ensures no deflection while the serviceable bushings offer a far superior ride to the bind of the factory bushings.