Detroit Locker
Overview: The Detroit Locker is an automatic locker that uses heavy springs and geared teeth to allow the outside wheel to spin faster when turning. In most applications the Detroit Locker is a replacement case, but for some axles-such as for the GM 14-bolt, Dana 70, and Rockwell-it drops into the stock carrier. We like them for front applications best, but have used them in the rear of longer-wheelbase vehicles with much success.
Street:
Keep in mind we've tested Detroits in short- and long-wheelbase vehicles. In a longer vehicle, the handling drawbacks aren't as bad, but the short stuff (like Wranglers) earns this locker a bad on-road score. Whether you're turning or going straight, or if you're on the gas, a Detroit Locker behaves just like a spool. When you let off the gas, the Detroit will unlock. This is especially noticeable in a rear application of a high-horsepower, manual-transmission, short-wheelbase vehicle-such as a V-8 Jeep-and the resulting loading and unloading can cause a violent jerking that you need to get used to. We've driven rigs with super-supple suspensions or no sway bar that have changed lanes from the action.
Off-road:
A Detroit Locker is a really strong differential, and about the only way we've seen them break is when they're violently loaded and unloaded-like when an axleshaft breaks. This vulnerability is the only reason the Detroit loses one point in the judgment. While you can lose some ability to turn when using it in a front application, we've had little trouble snaking through tight spots by modulating the gas pedal to allow the front differential to unlock periodically for tighter turning. We like the no-brain traction with no buttons to push or levers to pull.
Good: Tough as nails, no brain required to operate, insane traction when on the gas, and OK for front and rear applications.
Bad: On-road handling quirks, susceptible to damage from a broken axleshaft, and can be a little rough on the street in the rear of short Jeeps.
Ox Locker
Overview: An OX locker is a cable-operated locker. When disengaged, it's an open differential. When it's locked, it's a spool. The cases are burly, and the diff covers are heavy steel built to withstand rock hits and prevent deflection of the shift mechanism.
Street:
Since it's an open diff when unlocked, it's unnoticeable on the street. Make sure the cable is adjusted properly, or you may sense some ratcheting as the locking toothed gear attempts to drop into place.
Off-road:
Works well as a front or rear diff to help keep axle parts alive and allow you to turn more sharply. Older non-spring-loaded shifters can be difficult to engage in tight situations, but most of those have been swapped out and are off the market by now. The new version of the shifter is much better and easier to use.
Good: It's extremely strong and is an open diff when you want it, or a spool when you want it. Great for a daily driver or hard-core abused Jeep. Perfect for front and rear applications. Comes with a bomb-proof differential cover, and the beefy locking spool design will survive a catastrophic shaft or U-joint failure.
Bad: The cable must be adjusted properly or the unit will not function correctly, so make sure it's installed by somebody whose primary diet isn't bananas and peanuts from the zoo. Early shifter can be difficult to engage. The heavy industrial cable coming out of the cover can be vulnerable to trail debris in some applications. Also, the heavy cable needs to be routed into the cab, and the shifter is somewhat inconvenient to try to locate cleanly in a Wrangler or other vehicle with a small interior.