The Detroit Locker is an automatically-locking differential that was originally introduced in the early '40s as the "No-SPIN" differential. An automatic locker is one that locks both axleshafts together automatically when forward or reverse torque is applied to it. The Detroit Locker is designed to stay open otherwise, allowing wheel speed differentiation for normal driving. It doesn't engage until you accelerate, basically. The two most common complaints with an auto locker is that they engage and push the vehicle straight when accelerating out of a turn, and that they (harmlessly) clunk or bang occasionally-sometimes so loudly that you'll believe an axleshaft has broken.