its a powertrax lock-right
Extreme traction output.
The Powertrax Lock-Right and Performance Lockers' straight-line performance is equal to a solid spool axle, yet automatically unlocks to allow full differentiation in turns. The lockers also reduce the excessive noise, tire wear, and drivetrain damage associated with other lockers. Made in the U.S.A., Powertrax lockers replace the spider gears in your differential carrier without affecting your ring and pinion settings. The whole job can be done in your driveway with common hand tools in a couple of hours. A carrier is not included.
http://store.summitracing.com/largeimage.asp?part=PWT-1620-LR&Prod=Powertrax+Lock%2DRight+Lockers&img=pwt-2710_w.jpg
