Detroit locker for 87 and newer Ford 8.8" differential with 28 spline axles. for 4.88 and down with grind. The Detroit locker provides maximum traction for off-road or racing use. The heavy-duty case and internals provide a dramatic increase in strength while giving 100% torque to both tires. The mechanically-operated unit works by locking while under power and unlocking when you let off the gas, allowing you to turn. Unit comes standard with a one year warranty against workmanship defects.