My 02 cents and I think this common across several brands of CUT's, that is that heavy loading of the front axle in 4x4 is causing stub axle inner or outer ball bearing stamped steel cage to wear / distort just enough to release ball bearing(s) at that point it is just a matter of time till the hard, high carbon chromium steel ball bearings find their way between gear teeth.
Then it gets ugly because the ball bearing is so much tougher than the average cast iron gear teeth, something has to give, so the real carnage begins.
In one of the pics a loose ball bearing is visible. If they look through the destroyed parts I would wager at least one mangled bearing cage will be found.
It sure seems like there should be ball bearings made with stronger tougher cages / larger shafts / larger bearings in general or the manufacturers should/could possibly be using roller bearings.
Not much a guy can do beyond checking/changing the oil often. I like to lift the front tires of the ground occasionally and check each side for any "New" play.
Op, I hope you are able to find a complete front axle at a reasonable price and for no further front axle problems in the future.
One thing is for sure you are not alone on this, it has happened to quite a few CUT owners of several different makes over the years.