A traction bar, no matter the style, with a single link point at the axle and the frame bracket will bind leaf spring suspension. A shackle at the frame bracket allows the axle to move in an arc as the leaf spring suspension articulates. However, I don't believe you want to use a single bar type setup (2-link) with a shackle. Rather, a ladder type traction bar (3-link) with a shackle at the frame bracket.