This is a great way to upgrade from original leaf spring suspension. Unlike our competitors, Detroit Speed's exclusive new 4-link geometry design is uncompromised to achieve the best possible handling. The Detroit Speed "Swivel-Link™" (Patent No. 7,398,984) allows the suspension to fully articulate with smooth solid motion an no binding. The best feature is that this is achieved without heim-joints. Heim-joints are noisy and prone to short-term life. The Detroit Speed QUADRALink utilizes tuned high-durometer rubber bushings (in place of heim joints or squeaky urethane bushings). The long upper links provide great pinion and u-joint angle control. Contrary to competitors' kits, our kit utilizes a panhard rod that provides precise and effective rear axle lateral location during hard cornering. The panhard rod is adjustable as ride height changes for roll center control. The rear upper shock crossmember strengthens the rear body and frame section. Don't settle for anything less than our QUADRALink rear suspension!Double Adjustable Shock This is the most race winning shock JRi has in its stable. With its two independent adjustments and the enormous range of adjustment it can be set to the exacting demands of the driver and performance levels required while providing excellent ride quality on the street.Spring Rate: 250lbs/inSpring Free Length: 8in