Detroit locker for Model 20 differential. for 2.73 and down. 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.Detroit Locker