These premium springs are made using high quality spring steel to assure a smooth stable ride that will last for years. Ford originally listed more than 24 different springs for the Mustang between 1965-1973. The parts varied only slightly, depending on body style, options, engine size, handling options, and transmission. Scott Drake has chosen 2 different springs as the most universal and one of these should meet most customers' needs. This spring is the lighter duty of the 2 stock applications Drake offers and is best suited for 1965-1968 6-cylinder cars and stock 1965-1966 V8 cars with owner looking for a soft smooth ride. Caution this spring will sit the car lower than Drake's C5ZZ-5560 which has a mildly stiffer spring rate and will raise car a little higher than stock on lighter weight cars. Remember these cars sat low in the rear from the factory. So if looking to substantially raise up the rear of your Mustang this spring is not your best option order part number C5ZZ-5560 instead. Features orginal style clamps, correct "hot cupped" ends, anti-squeak pads, front eye bushing installed and original 4 leaf design. This spring is compatible with 1969-1973 Mustangs but may sit too low too low for most 1969-1973 owners. Heavy Duty stock version is sold under part number C5ZZ-5560 and is recommended for 1969-1973 owners if going with a stock 4 leaf spring and wishing to raise the back end up.