the ingalls kit slides for different degrees of correctness. i believe the piece which bolts the upper arm to the frame of the car. either that or the ball joint i'm not positive. (i've only seen pix of the ingalls kit)

on the progress you have 2 settings you can choose. one is for a mild drop and the other is for a more excessive drop. they tell you which one to choose depending on drop, and alignment and stuff.

with the ingalls kit you slide it to the degree of correctness you want, and torque down a bolt (i believe) to set it in place. i've heard of the ingalls kit slipping alot. my friends kit slipped. he hated it, plus his wheels sat out further.

i had the progress kit, but i never installed it, i was gonna buy the skunk2 kit which replaces the whole arm. on the skunk2 kit it has an adjustable ball joint which slides to the degrees of adjustment you want, and you tighten down 4 bolts. which are suppose to keep it in place. lots of people swear by the skunk2 stuff, but i'm weary of it. just cause it slides.