Just a thought here. When I had superior axles in my AMC 20 the bearing had the small end towards the Diff. On my Summers Brothers axles the small end of the bearing is faced towards the wheel. Could you have gotten he bearing in backwards. Most shops wouldn't know which direction the bearing goes without prior knowledge of that brand of axle or having the install instructions on hand.
Just something you should look at since having it in wrong could lead to the bearing working loose.
In the Land of the Political Tree Huggers. Old CJ-8 looking for a trail to travel while making a new adventure to remember.