Also, Check the gear lube in the front diff / transmission.
 
	Loose nut is not good for anything - bearings, axle, hub, cone washer.
 
	Sealed bearings, might not be good.  Depends on what they were sold as.  
	I once used electric motor sealed bearings for the idlers, and they did not hold up as well as the oem ones, or the proper ones I bought from a bearing supply shop next time.
 
	Different applications, but something similar regarding loading and or temperature may be similar.