A differential, what does it do??
When a vehicle is negotiating a corner, the outside wheel has to travel a greater distance than the inside wheel. Therefore the outside wheel must turn faster than the inside wheel. The differential is the device within an axle assembly that differentiates the wheel speed between the two wheels. The differential also transmits the power from the ring gear to the axle shafts and determine how much power is delivered to each axle.
	Conventional differential The conventional differential transmits power though a set of spider and side gears to the axle shafts. Power is normally equal to both shafts. But, if one wheel slips, the other wheel receives very little power. This differential is fitted as standard equipment on most vehicles due.
	Limited slip differential While similar to conventional differentials, limited slip type differentials add a friction medium to the assembly to maintain equal power to both axles even if one tire begins to slip. When load is applied to the differential, the friction plates are also loaded, causing a good positive power flow to both tires.
	Automatic Locking differential This type of differential transmits power to the tires through a set of locking dog clutches. This unit provides automatic locking action that will keep both axles locked together even if a tire leaves the ground. Severe off-roading demands this type of differential.
	Manual Locking Differential Manual locking differentials offer the driver the option of choosing between a  conventional or a fully locked differential at the touch of a button (cable, etc.). This provides versatility in a vehicle that will be used in both street and extreme off road situations.
Mine (in the rear) is welded, therefore acting as a Automatic or manual locking dif, it just doesn't unlock