The extension bracket ensures correct bump stop clearance and prevent suspension from bottoming out for Super Duty vehicle. It's for 2-4" lift kit.
Determine your lift kit requirements based off current stock heights (displayed in green) for both front and rear by measuring from the ground to the bottom of your vehicle's flare.
Level to your stock rear measurements by adding appropriate lift to the front of your vehicle.
Add to both front and rear equally to gain lift while retaining the stock appearance.
Achieve a leveled lift by adding to both front and rear while accounting for the stock difference.