Quick Lesson:
http://www.illconformity.com/videos/linkvideo.wmv
what a lot of people don't realize is the setups like the KP 6 link and SD 5 link that I think are trying to be duplicated with some of the new ideas are still entirely forward link setups. The rear lift bars are mounted on a shackle or dogbone, so they have a double pivot at the axle. That way they can only move it up and down, but do not locate it or effect pinion angle in any way.