Bergman Auto Craft leaf spring shims. These are designed to correct thrust angle issues by squaring the rear axle to the frame. Typically, one side of the rear axle is closer to the front wheels than the other. Simply place shims between the front leaf spring hanger and the frame one at a time until thrust angle is zero or as to zero as possible. These shims are 1/8″ thick and typically one or two are required. Sold each. Corrects thrust angle Insert between front spring hanger and frame. Provides the ability to square rear axle to chassis 1/8″ Thick.