It won't sag if you get the shackle angle correct. I added a pic to my first post. You should get new u-bolts, and may or may not need to use the factory angles blockes depending on how your pinion angle is. I'm not using any blockes at all, and a pair of new u-bolts for the Sterling 10.25" axle were about $30. This mod will move the axle about 1-1/2" forward, so the wheel won't be centered in the wheel opening. I found a set of 1" thick, zero-rate blocks with an offset center pin hole that I may try out later on to re-center the axle. But if I don't get any tire contact with the rear quarter panels, I'll leave them out. Hardest part was removing the rivets from the F-350 hangers on the original truck. JSM84