The Detroit Speed Speed Kit 1 kit is designed to lower the ride height of your 1973-87 GM C10 Square Body truck 3-4 inches in the rear. The Speed 1 kit includes the Detroit Speed leaf spring front drop hangers and drop shackles. Both the shackles and hangers feature two leaf spring mounting options that are one inch apart to give you more adjustability in the stance of your truck. All mounting hardware is included in this kit.