The Detroit Speed leaf spring rear drop shackles are designed to lower the ride height of your 1973-87 GM C10 Square Body truck 1 to 2 inches in the rear. They are manufactured from high-quality 1/4" thick steel and powder-coated black for durability. Detroit Speed has designed this shackle with two leaf spring mounting options that are one inch apart to give you more adjustability in the stance of your truck.