Well I purchased a set a rear Timbrens for my truck. After one week of testing, I decided to return them, here is why. Extremely easy install, that's a given. They absolutely minimized the rock...
Timbrens are great on my F-150, when the camper is on. 1" of spacing unloaded as the instructions say.
With the camper off, and me towing just my boat, they kinda suck. Too stiff without the camper, and the boat weighs just enough to barely preload them.