I've bought another diff and installed a Quaife ATB LSD in it. Getting the castellated nut thingies out was the hardest part of the job in my case. Here's a tool I made:
That's the fourth version. The previous ones had the nut welded just on the inside, then additionally a couple of tacks outside, then more, and finally this full weld. Anything less than a full weld and the nut did not stay attached to the plate for more than about one turn of the nut. I had to strap the diff to a big plank and turn the nut with a ~1.5 metre pipe. The o-ring got caked in place and sheared and crumbled as I undid the one of the nuts.