Here you go:
http://www.allpar.com/ed/suv-suspensions.html"Unequal length control arm suspensions are the most complex of the designs considered, but also, potentially, the most "tunable" thanks to the isolation and adjustability of the various dynamic parameters, such as anti-dive, roll control, anti-squat, travel, etc. This very complexity entails analysis and determination of desired handling characteristics far more demanding, however. All of the manufacturers of Class 1/2/3/4/5 trucks have utilized this basic design over the years, but cost of the components has continued to be a justification stumbling block.
The term "unequal length" comes from the fact that, by design, the pivot length of the upper control arm (UCA) is shorter than the lower control arm (LCA). This is measured between the pivot axis and the ball joint, forming the triangle or "A" shape. Usually, the LCA is the longer of the 2 arms and travels through the lower measurement chord arc height. The UCA, being shorter, travels through a shorter chord arc height. (This means the chord arc height is measured horizontally.) The upper control arm moves the top of the tire a greater distance laterally in the vehicle than the lower control arm moves the GCP. This means, in a dynamic condition, the the tire wobbles at the top a lot more than the ground contact patch. This instability is what must be controlled by the geometry design to prevent a vehicle roll-over condition and directional instability."
