differential holding fixture

I am looking for a holder to hold the pumpkin out of my 8 3/4 rear end while I set up the new 3.55 gears...Something like what a shop would use..I just dont know where to find one. Something I can stick in my engine stand and rotate the diff when necessary. All I have now is a workbench to set the diff on. It moves all over when you try to work on it.