I used the shackles to lower the rear (to level) since they are variable height adjustable. I have experienced drivetrain vibrations in this truck since day one, and these shackles seem to have made vibrations worse. I think the pinion angle changed enough when lowering that I felt the vibrations. Really don't need these shackles for any other reason besides leveling, and with the camper shell and tool box I have in the truck now, the rear is a touch lower than the front. OE shackles are still good, so I put them back on. I'm also purging and liquidating some of the crap I've accumulated over the years.