YJs have solid axles with leaf springs at both front and rear ends. Lift is achieved by replacing the four springs. Two types of Superide front springs are available for the 3.5" system. The four-cylinder / light-duty six-cylinder springs are designed for excellent ride quality and articulation on lightweight Wranglers with soft tops and no heavy accessories. The heavier-rated six-cylinder springs are designed for vehicles equipped with heavy accessories (such as those equipped with a hard-top and winch) and have proven to stand up to serious off-road use. They are also an excellent choice for Wranglers equipped with a V-8 conversion. Either way, our 3.5" system has earned the reputation of being the YJ lift to have. It has just the right balance of stability and flexibility