Offset shackles
They offset the springs a 1/2”, so that’s what you get. DoctorDiff’s are nicer than the Mopar Performance version, which claims it’s a 3/4” offset. Which isn’t true. The front hangers can only be offset a 1/2” before they hit the frame rail in the front. So on the MP kit the hangers are offset a 1/2”, the rear shackles are offset 3/4”, and you put a 1/4” worth of bind on the springs.
The doctordiff kit uses better hardware, so you don’t have to cut a hole in the frame rails for clearance like you do for the MP kit.