I don't know the specifics of your axle, but generally speaking yes you can add a limited slip. There are a variety of lockers/limited slips on the market to do what you want. there are certainly others, but the first limited slip only that comes to my mind is the detroit truetrac.
just be prepared to have it installed...which will end up being probably as much as the limited slip unit itself.
now if you want a lunchbox style locker, they are much cheaper and you can install it yourself.
2008 CRD GC