There are several different modes of converting longitudinal (front to back) rotational motion to transverse (side to side) rotational motion, mainly in differential and non-differential apparati:
1. Differential- these include limited-slip, detroit locker, locker, open, etc. The meaning of "differential" is that (housed in the rearend) it allows the wheels to spin at
different speeds, such as when going around a corner. The different names are simply defining the system of clutches, etc. that allow the driveshaft to articulate with the axles differently. Limited Slip differential read whether or not one side or the other is slipping and consequently delivers power to the other side. A locker rearend transfers power to
both wheels
all the time your foot is making the gas pedal feel familiar with the floor
(similar to direct drive on roots-type supercharger applications; however, the locker will allow the wheels to spin at different rates so you can still corner without braking an axle). Open rearends can transfer power to both wheels, butwhen power-braking to do a burnout you'll only see one of the donuts makin' a cloud (occasionaly, both will spin due to force exerted on one axle by the other) I have an open rearend on my '69 Mach I, and I've done burnouts on both wheels before as well as one whell, then the other (the jist of the open rearend is that one wheel or the other will (usually) spin)
2. Non-differential= spool. Imagine a beefy, enlarged washer with a pipe running through it at a 90 degree angle- the axles fit into the "pipe" portion of our model, and the ring gear is bolted to the washer. The pinion makes contact with the ring and that's where the magic happens- all power is transferred to both wheels all the time direct-drive style; however, as the axles and thus wheels can't spin at different rates, you'll break an axle if you try to corner at a radius of less than about 50 ft (keep an eye on the super-stock and top fuel dragsters at the end of the 1320 and see how wide their trucks have to tow them around a corner). This type of rearend is STRICTLY for dragrace-only, straight-line applications.
If you want a massive amount of performance for the street and don't mind a slight clicking sound around the corners, the locker differential is for you. Open is the cheapest, and I can still spin both my tires going around a corner, however, limited slip will give you the benefit of both wheels spinning all the time (it's just that whole "taking power away" deal that gives me the willies...)
Sorry for talking your ears off, fellas; however, I've taken a lot of advice from the guys in this forum and thought I'd give a little back. Hope this helps and Happy Holidays! (so many H's...)
locker vs. spool 
