Just to set your minds at ease, I do the proper maintenance after every trip. But, after over twenty five years of removing the diff. covers and repacking the bearings, I am ready to try to keep the water out. Sometimes, I am in the bush for weeks at a time and cannot remove the covers every time I make a water crossing. I have drilled and tapped drain holes in the differentials, so I don't have to remove the cover in the field, but capturing and transporting the fluid (as well as bringing in gallons of new fluid) is a PITA. As for the wheel bearings, some of the people I wheel with have installed zerk fittings in the front hub and just keep pumping grease in there and don't have any problems.