Suspention

The upper control arms are completely removed in favor of a ladder bar (16), to improve traction on street tires. It is attached to the passenger side of the aluminum alloy differential cover (5) that has a 60,000 psi yield strength. The front mount of the ladder bar attaches to a frame crossmember (13) about midway under the car, which also serves as a driveshaft loop.

During a brake stand in a rear wheel drive car, there is a tremendous amount of torque building against the staionary rear wheels. The torque load about the driveshaft has a tendancy to lift the left side of the car and squat the right side. The GNX ladder bar channels the rear axle twisting energy like a lever to apply upward lift at the midway frame cross member. The lift is applied slightly off-center to the right side, and thus equalizes the natural lift from the driveshaft torque to the left side. The result is an even rear-end lift of several inches. When you let the brake go, the rear drops evenly and the car charges straight. (See it in action in the GNXvsVette video )

Remember the upper control arms were removed to accomodate the ladder bar movement, so a panhard rod (20) and frame brace (2) are added to control lateral motion of the rear axle. These are located right behind the rear axle. In some of the GNX literature, the panhard rod is labeled incorrectly. The panhard rod goes from the left lower trailing arm mount (21) slightly upward to the right frame rail mount (11). Then, the frame brace rod goes back across (upward) to the other frame rail (1). This setup keeps the rear axle stiff during cornering.
Here is a picture of the less accurate diagram of the rear suspension that is from the GNX book. It may help you understand how things are positioned, but the mounts and labeling are incorrect. The panhard rod is missing and what is labeled "panhard rod" is actually the support brace. The ladder bar is pictured & mounted differently, and the driveshaft loop looks nothing like that. This was probably a pre-production exhibit.