Front Pro Coil single adjustable stock mount shock kit. Includes 10" spring with rating of 400 and a flat end. QA1 Pro Coil Systems for 1964-1973 Mustangs are a great option for anyone looking for fully adjustable ride height and valving control. Choose a spring rate and adjustability that fits your driving style, adjust the valving to match, and you are on your way. These shocks also utilize a fully threaded body that allows you to adjust your ride height for the perfect stance or to finely tune the weight balance for superior handling.