The rear suspension in the GM B-Body is what's known as a triangulated 4-link.  This style of rear suspension has proven itself over the years and is very common, even the majority of Mustangs on the street have this system. The upper and lower rear control arms constitute the four links in this rear suspension.   The upper arms locate the axle side-to-side and hold the pinion angle. The lower arms locate the axle front-to-back and transmit the wheels' thrust to the chassis.  Note that the control arms are not parallel to each other.

When the car leans in a turn, one side of the chassis moves upward relative to the rear axle, the other side moves downward, and these non-parallel control arms must twist and change length axially to allow the axle to articulate.   This causes the control arm bushings to bind.   If this bind becomes excessive, it can effectively create a very stiff rear suspension and produce sudden changes in handling (oversteer).

GM minimizes this suspension bind by using compliant rubber bushings in both the upper and lower control arms and the arms themselves can flex.   These relatively "soft" bushings and arms accommodate the necessary motion of the control arms during body roll.   However, they also permit wheel hop on hard launches and horizontal axle deflection in aggressive turns.  This deflection is responsible for the loose rear end sensation well known to anyone who has driven their B-Body aggressively.

The factory control arms on the GM B-Body definitely leave a lot to be desired for the driver that wishes to push their car to the edge.  Correcting these shortcomings was the goal in designing the arms you see here.  These tubular arms have the following features:

Adjustability.  Both the uppers and lowers are adjustable. This allows for the centering of the wheel in the wheel well with the lower and adjusting pinion angle with the upper.  Other companies offer "extend" lowers in +0.5 or +0.75, but with these arms you can adjust them to be perfect for your wheel/tire combination.

Spherical Bushing. Both the upper and lowers have greasable spherical bushings at the frame mount end.  These units allow 30 degrees of travel and are nearly "bullet proof" as they were designed for off road truck use.  They also have a long service life that is provided by quality components and their ability to accept grease.  In addition, if one of the spherical bushings ever does wear out it can be easily removed and rebuilt in your own garage.

Massive Tubing.  The lower arm is built with 1 3/4" x .281 wall tubing.  This thick wall tubing will hold up to all the abuse you can throw at it and will support the thickest rear sway bars you can find.

Other Features:

Greasable poly bushing on rear of lower arm.

Laser cut and Tig welded construction on upper box end.

Powder coated black.

New hardware for sway bar mount.