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 1964-1973. 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 we offer and is best suited for 1964-1968 6 cyl cars and stock 64-66 V8 cars with owner looking for a soft smooth ride. Caution this spring will sit the car lower than our C5ZZ-5560 which has a mildly stiffer spring rate and will raise car a little higher than stock on lighter weight cars. Remember Mustangs 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 O.E.M. style clamps, correct "hot cupped" ends, anti-squeak pads, front eye bushing installed ans O.E.M. 4 leaf design. This will fit 69-73 Mustangs but may sit too low too low for most 69-73 Owners. Heavy Duty stock version is sold under part number C5ZZ-5560 and is recommended for 69-73 owners if going with a stock 4 leaf spring and wishing to raise the back end up.