SPL's CNC machined T6061 aluminum differential mounting bushings will hold the differential solidly to the subframe, significantly reducing wheel hop and improving power transfer to the ground. Reducing movement of the differential during hard launches will also help prevent damage the drive shaft and half shafts. SPL's bushing set includes the front bushings that press onto the pumpkin as well as the rear bushings that press onto the subframe. Beware of other bushing kits that do not include the rear bushings (SPL's kits have 6 pieces to their 4 pieces)! Only SPL's solid differential bushings are correctly engineered to hold the differential solidly at all points to prevent damage to the differential and eliminate movement of the differential for best performance.