There is no oil getting from the axle to the hub. There is a seal (two of them, actually) to keep the oil in the diff.
There is no oil in the knuckle at all. The TM says chassis grease... that's basically peanut butter.
I've seen a fair share of G056/508 hubs and most of them had hard packed grease in the hub... it simply never gets agitated. The CV joint does nothing of the sort.
Filling the knuckle with grease is very, very old school. Every modern CV joint is greased, and that's it. The boot is there simply to keep dirt out.
Just offering a suggestion.
Any chance that you put radio's back in the truck?
