for the nasty MolyB grease in the hub area use rubber gloves and lots of paper towels. Past the knuckle/hub, there shouldn't be any grease in the actual axle housing; usually if there's a seal problem there it's the gear oil from the diff making its way into the hub, not the other way around. If...
Like Hokie said, don't waste new gear oil on the front diff by "flushing" it, it's not a radiator or engine...not the same concept. Search for the 60 series chassis FSM on this site, download and read, it's what you are looking for as far as instructions on how to do the knuckle repair/service...