Upgrading to a 40 spline drive flange kit dramatically improves axle strength by increasing spline engagement and reducing the chance of failure under load. This design replaces weaker factory lockout hubs with a solid, mechanical connection—ideal for high-horsepower or aggressive off-road vehicles. The Crane Axle 40 Spline system ensures that torque is evenly distributed and that your drivetrain can handle the punishment of modern off-road performance without compromise.