Our Speed kits are designed to make your A-Body maintain optimum geometry and tire contact through the full range of rear suspension travel. Through the use of our patented Swivel-Links™, the rear end housing becomes fully articulated, without the use of noisy spherical heim joints. With the Swivel-Links™ pinion angle and/or wheelbase can be adjusted without unbolting the link from the car. The Detroit Speed tubular rear Anti-Roll bar attaches to the chassis for a substantial improvement in cornering ability. Our rear Speed Kit springs, shock absorbers and sway bars are designed to complement the front Detroit Speed Kits, giving your classic contemporary handling and ride quality on par with the latest modern muscle cars.Spring Rate: 150lbs/inSpring Free Length: 12.75in