If you try to lower Super Duty with springs you get trouble, if you heat or cut your springs, even if you use a "lowering" spring you cause alignment issues you just can't correct out! The fabricated "I-beam" type parts suffer from "weld creep" as they are welded, which simply means they warp a little. That makes it hard to get consistent finished parts! You only need to remove the factory beams and replace with DreamBeams and you have a 3" drop with the factory coils, full suspension travel and all the goodness that comes with that.
The rear end is done with a tried and true Hanger/Shackle kit. This moves the mounting points of the leaf springs up on the frame providing the lowering needed to match the front! A bolt on 3/5 kit for your SuperDuty, simple installation is a DJM trait.
Shocks are NOT included