As far as I am concerned these diffs are the real deal for the way I use my truck. Its so awesome to be able to go bash hard for a day and come home with no stripped diffs. In my experience diff slop in the bulkhead will cause you to strip gears.
There should be no play on the diff and it should be nice snug fit held firmly in place. A diff floating in the bulk will strip gears every time. This is from my Summit build thread on how I went about trying to fix diff slop in the bulks.