Blocks are available in 1 to 4-inch sizes. Dropped leaf springs replace the stock leaf springs. The leaf springs shown are a mono-leaf design. Using dropped leaf springs usually means sacrificing some of your payload capacity. Drop leaf springs are available in 1 to 5-inch drop applications.
Flip kits relocate the axle from below the leaf springs to above.
It is necessary to notch the rear frame rail on a truck so that the axle can have proper travel. This is necessary with any drop of 6-inches or greater. A metal reinforcement is bolted to the frame so that a couple inches can be notched out. Airbags can be added to the rear of a truck. They provide an adjustable ride, load-leveling capabilities, and even ride height adjustment.