....and you oughta check and see if you did any other damage. If you hit the curb that hard, it's possible you've damaged other components too - check the wheel - it's likely bent; check suspension pick-up points; and once you get it back together, see if the rear end is making noises and if the posi is still working. Lastly, probably ought to have a shop check the alignment, and take a look at the tire in question. If it wasn't destroyed in the impact, it may well have separated a belt internally which can lead to vibrations and failure.