The TRD Locker disengages at 5 mph. Most after market lockers can be left engaged at any speed. Limited slips are always engaged, most have a clutch that "limits slip." Lockers will provide much more traction as the split power to each wheel 50/50. If you are going to be doing much road driving go with a limited slip or a manual locker, such as ARB or TRD. An auto locker will engage itself as you go around turns while driving on streets cauzing the back end to hop (assuming it is a rear locker). Automatic lockers makes driving on wet roads difficult, near impossible on snow and ice coverd roads. A limited slip on the other hand will improve traction on wet or icy roads, but not improve traction as much off road as lcoker does. In the Rocks or on trails the TRD is a great locker because when you need it you shouldn't be going over 5 mph. On Sand or Mud on the other hand you will most likely be driving at speeds well above 5 mph as you need to keep momentum up. An ARB (manual) or a Detroit, Lock Rite, ect. (automatic) will provide great traction in mud or sand. A limited slip is good every where, not great off road and not terrible on road. The best in my oppinion is the ARB, but it is pricey as you will need an on board air compressors to activate it. I hope that helps... Good luck and have fun.