When I bought mine, the previous owner did the single piece axle. The two piece axles, from what I’ve read, can fall out. Single axle removes that weak point.
The axle tubes are thin and have been known to rotate from the housing, which is corrected by what Ron said above, do four 1” inch welds, and alternate the welds to each tube to minimize warping. Again, searchers has a nice truss kit, assembled or diy.
The gears in the 20 are beefier than a Dana 44. And when it has welded tubes, a truss and single piece axles, they are just as good, if not better than a 44.
A truss is in my future for my cj8, but with the limited off roading around my way, it’s a low priority