Installing A Rear Lsd In A Non-lsd 2g?

[1badgsx]

I have a 98 GSX without a rear LSD. I was wondering what parts I would need to put a factory unit in. Will I be able to just install the LSD or will I have to install the entire LSD rear end? Is there an aftermarket unit that will fit in my rear diff? I have been surfing many sites for this and haven't found much of anything.

Thanks,
-J