These Shackle Hangers are HEAVY DUTY! Milled out of a solid block of steel. Mount with 3 bolts instead of 2 like stock hangers do. Front uses existing hole already in the frame. Rear needs extra hole drilled (I used a 21/36 bit) and the frame had slots on each side where the new hole was drilled so I was about to put the bolt through the slot in the frame and through the hole and get it bolted up. They cost $145.08 for the set of 4 with grade 8 mounting hardware. Worth every penny!