Designed for use in the Ford 9" style 3rd member with a billet or forged performance case and bearing support capable of handling 9.5" and 10" diameter ring gears and 35-Spline, big pinion bearings. Engineered and built for high horsepower racing applications from 1,500-4,500 HP and have proven to reliably deliver maximum power from the flywheel to the tire. Made with the highest quality 4130 Steel, shot peened and tooth ground for unmatched precision, Pro-Power Gears are fast becoming the required choice for both serious sportsman and professional racing teams!