The Trac-Loc Limited Slip Differential is designed as a direct replacement for the hard to find expensive OEM unit, or for those enthusiasts desiring to convert to a limited slip. Available for 9 Ford rear ends, this nodular steel casting is totally rebuildable, includes nickel steel side gears and pinion gears, and multiple plate 360-degree steel clutches. This extremely tough and durable differential houses 400-ft/lb static springs, and is capable of 150 lb. braking torque. Available in 28 or 31 spline.