It is possible that it could be "both". Detroit makes a full case locker as well as a lunchbox locker. The only way to really determine what your jeep has is to pull the diff cover off. If you decide to do this (which is a very simple task) here are pictures of what to look for.
This is a Detroit EZ locker. It is Detroit's lunchbox. Just about every lunchbox will look the same.
This is the Detroit Softlocker...their full case locker.