A wheel bearing lubricated by diff oil?
That made me think as well.
If you look at the exploded view of the BTR axle on Morganatica you can see that the oil seal is outboard of the bearing and there is no other seal between the diff and the outer bearing. As the oil level seems to be slightly above the bottom of the axle tubes then I guess it's feasible but I'd like someone more knowledgable to confirm either way.
BTR axle 
