I don't like spools, and like Lincoln Lockers even less.
That said, I had to get the TJ ready to lead for an event and set up a new carrier for the 8 3/4 by welding the diff- that was over 2 years ago, and I have put better than 20K mi on it, as a DD. I hate the way it turns, both on the street and on the trail, but it has held up. (I have been too lazy to pull the third and install a locker)
Make sure you weld it well- I welded the spiders together, and then to the carrier, which was much easier to do with the drop out third member that the 8 3/4 has. Put some serious heat into it and build some good welds where the spiders mesh, but make sure you will still be able to pull the axleshafts.
Michigan- The Only
Great Lakes State South of the Mason-Dixon Line.