[kookykrispy]

I had 'lock-right' no-slip lockers in both front and rear Dana 44's of a jeep I used to have. I can't recall if mine were made by powertrax or some other brand, but I think we are talking about the same product more or less. The locker installs in place of the spider gears of your old open differential. You still use the same carrier, but the locker is inside. Was great in the old jeep, easy to install, nearly unstoppable on the trails off road, but you just have to be willing to put up with how a locker acts on the street.
When you go around a corner, your axle is either audibly clicking, as the teeth in the locker pass over each other to allow the outside wheel to turn faster than the inside... or if you're on the gas, both axles are locked and you're chirping the inside tire.
The 'feels like the rear moves to the side' statement made by 77vettejeff above is from the locker engaging or disengaging one side or the other. As the locker locks or unlocks, the torque is applied or removed from one side of the rearend, so it can feel like the axle shifts to one side or the other. This is normal, but kind of odd, if you are used to driving a limited slip rear or an open diff.
I like lockers because they are tough and probably won't break. I twisted up an axle shaft in the rear of the jeep, but the locker was just fine. I had some moser forged shafts custom made, and after that it was bomb-proof.
Keep in mind your locker is either engaged or not engaged, there is no middle ground like on a limited slip... when it is engaged, it acts like a spool, there is no differential action, both shafts are locked together... so you need to be careful to slow down or let off the accelerator when taking corners, especially in the rain, the rear end likes to break loose if you are on the gas.
I would use one on the street, but only in a more drag oriented street/strip car where I was focused more on reliable straight line traction and didn't care about doing road-race type cornering.