I have always read that you dont want to pack the hubs, just enough to cover everything but not packed...
The wear I have seen here is due to engaging the hubs and then, even though they may not be perfectly lined up, the operator gets in and gives it some throttle, more than just idling in 1st gear and as the axle accelerates, if not properly seated in the hub yet, strips away the edge splines...keep doing this until the hub splines are so weak, they are just gone...
brute4c