Ok I bought a lunchbox locker from a friend of a friend last year before I knew much about XJs and the guy told me it would work in my rear axle but I'm pretty sure he thought I had a Dana 35, come to find out I have a Chrysler 8.25. So, I wanted to make sure I'm remembering this convo correctly, and see if there is any way to tell for sure which rear end this locker is for. Aside from looking at pictures on the Internet.

 

Figure out for sure which axle you have. Then scan the locker for any part numbers, punch them in google and see what comes up. It should bring you to a link that shows what locker you have and for what axle.

 

Two things that might tell you.

Count the splines inside one side gear.
Use a micro/caliper to get the exact OD of the side gear that goes into the carrier.

If you get lucky and count 29splines then its for sure a 8.25..