SPC Performance THRUST ALIGN PLATE 2.5in.Our patented thrust alignment plate will allow for corrections of setback and thrust angle on most vehicles with rear leaf springs. Installation is made by loosening the U bolts holding the leaf spring to the axle, installing the alignment plate betweenthe axle and leaf spring and retightening the U bolts. Widths are availalbe in 2 3 8" and 3", and each kit comes with multiple parts to provide coverage of most vehicles with rear leaf springs,