There are many different types of differentials on the market today. The early Bronco came from the factory with either an open or a limited slip (posi) type differential. The open differential transmits the power through just one axle. This leaves a lot to be desired in off-road situations.
The limited slip units are more desirable. They use internal clutch packs to transmit power to both axles. When you go around a corner these clutch packs allow slip so the outside wheel can turn faster. This "slip" can be the thing that causes frustration off-road because these units can slip right at the point where you need power at both wheels. A driver with finesse can get a lot out of a limited slip unit and they are quiet and for the most part trouble free.
That brings us to locking differentials. The legendary Detroit Locker has been proven over the test of time. The Detroit is the choice of many hard core wheelers because of its simplicity. Install it and forget about it. The Detroit is a fully automatic locking differential and is completely maintenance free. Next we have the ARB air locker. The beauty of these is the ability of the driver to turn them on and off with the flip of a switch. This is the choice of many off-roaders who also drive a lot on the street.
ARB Air Locker
AIR OPERATED LOCKING DIFFERENTIALS
Quiet smooth operation on the road with no adverse affects on tires or handling. When you get to the ruff stuff just hit the switch and now you have a fully locked front end, rearend or both. The ARB air locker has been around over 15 years. They have been tested at about every hard-core wheeling spot on the earth and have proven their performance and reliability. So how does it work? Hit the switch and in one tenth of a second compressed air actuates a piston inside the differential which engages a locking gear, instantly locking the differential and directing torque to both driving wheels. Once you get through the hard spot just hit the switch and the differential lock is disengaged.