When lifting the front of the Super Duty 3 – 3.5″, the factory caster is reduced by approximately 1.5°. For the 2020-23 Super Duty, we provide a 2° caster shim which is enough to restore this caster and add a touch more – unfortunately, this “touch more” is rarely enough for proper tracking. This leaves us recommending our Adjustable Radius Arms proven to add an additional 2.5° of caster (when maxed). Combining the Carli Arms and 2° shims results in a Super Duty on 37″ tires that holds a lane, and returns to center after a turn, better than a stock truck.