Installed a set on my 2005 F-250 4x4 last week. Piece of cake. Just remove the OEM bumper stops (yellow, hanging off the frame above and behind each rear wheel), assemble the Timbrens, and bolt them on. The hardest part on my intallation was removing the factory bump stops. They sprayed some undercoating on the frame and bolts and must have also used some type of Locktite-like material, they were a bear to turn off. Assemble the Timbrens BEFORE bolting the bracket to the frame, much easier. You'll have to figure out which of the three holes in the bracket to use to ensure that the Timbrens sit directly over the axle. The kit came with a large rubber spacer for each side, I didn't need them on my installation.
Before I installed them, the truck would sit down about 2.25 inches when I lowered the 5ver on it. With the Timbrens, it sat down only one inch. Side to side sway was eliminated too. Well worth the $154.95.