When you change rearends, raise or lower your car, or change tire sizes, the driveline angle is affected. With the stock (rigid) arms there was no way to compensate for these changes. Now you can adjust your pinion angle for any modification or application with CurrecTrac® Adjustable Upper Control Arms. You can align your pinion angle with the drive shaft for maximum performance and improved reliability. Adjustments can be made right on the vehicle without removing the arms.