Mini Spool for Ford 9.0 with 31 spline axles. Cross is bored for three cross pins. Mini spools are a low-cost traction option for vehicles looking for full-time lockup. The mini spool installs into a standard open carrier and give 100% power to both tires at all times. These units are not recommended for street-driven vehicles. We recommend full spools for vehicles with large tires or high horsepower. These units come with a one year warranty against manufacturing defects.