Because of the variation of factory rear lifts, the Pro Comp kit uses a 1-inch block in conjunction with the stock block and add-a-leaf, depending on what is needed. A replacement leaf pack will soon be available, which is good since we frown on slacking blocks. However, you’ll have to front the extra money for the option. Slip the new U-bolts over the axletube along their mounts and torque the U-bolt nuts to 115 lb-ft. The brake lines may become taut and need a little more stretch. Using pliers, bend the brake line bracket towards you about 90 degrees.