Measurements, a friend that has a machine shop to notch that 4x4 tubing to fit the frame, and the mouth of a sailor when you realize how much swearing you are gonna do. Haha! Test fit everything 5 times before laying the weld down. If your doing shackles rear and hard mounted front like mine figure out were you want the front crossmember first then tack it on then figure out the back tack on, use jack to apply all of trucks weight to leaf to see if you like the amount of shackle angle with the weight of the truck on it. If you like it weld it. I also used a small pole to run threw both holes of the shackle on both sides to see if they matched up. Have freakn fun with it. If its not a daily driver take your time.