I have the same problem with mine, spoke to a few mechanics at work, they all ay the same thing:
clutches in the lsd - replace fluid, if there not too worn, they will come good.
backlash in the diff- take it to a diff place to get the backlash adjusted
uni joints - sometime u can feel some play in the tailshaft, but not always. when in doubt, take them out and replace them.
i changed my diff oil, no change, so the next thing is to replace the uni's. its the cheaper option, and id rather spend $50 bucks to get new uni's, than take it in to a diff place, which would cost a heap more.
will post her when i have done it, and let u know if it fixed the problem.