In leaf spring type suspensions, there are significant forces focused on the pivot points and shackles. For this reason, it is imperative to replace the soft, blown-out OEM rubber bushings. Why not replace them with a set of these Prothane leaf spring and shackle bushings? They're made of premium grade polyurethane and precision fabricated for a perfect fit. Plus, they won't wear out or deteriorate like the stock set. Who could ask for more?