I put them on mine when I moved the springs into the frame rails. It allows it to sit 1/2 to 3/4" lower in the rear which is what I wanted. Only difference I noticed is on the street they pop at times when I turn sharp but I have a Dana with a spool. If you install them make sure to have the slide bolt set 3/4 of the way to the rear with the weight of the car on them or they will bottom out during the launch as the spring arches.