Here is a way to check to see if you have a locker installed. Check the rear axel. If you have a locker it will act like the discription following:
"Now as a final test, put the transmission in gear to lock the driveshaft. Next, have a helper rotate the passenger’s-side wheel (axle) in a forward direction until it stops and hold it. This side is now locked. Now, rotate the driver’s-side wheel in the opposite (reverse) direction. The Locker should click as the Coupler attached to the axle rotates. Now have your helper rotate the same wheel in a reverse direction until it stops and hold it. Now, rotate the driver’s-side wheel in the opposite (forward) direction and again you should hear the clicking sound. Have your helper change sides and perform the same test. If your measurements and tests have been successfully completed the unit has been installed correctly and you are now ready to install the differential cover and add the required amount of fluid."
This was for a "lunchbox" type locker like Powertrax. Hope this helps.
2005 Fire Red Rubicon 6-speed
2010 JK Rubicon Auto Dark Charcoal Pearl - fairly stock