3rd gen wheel bearing maintenance

I hear the rear ball bearing wheel bearings are worse than the 2nd gens. Can the front and rear wheel bearings be greased by a fitting, are they sealed or does one use the old bearing packing with a wad of grease in your palm method?
How often should a person service them?

They are not intended to be lubed and I think if you pulled the rear shafts to lube them, you'd risk boogering the seal, and then you have to remove the bearing, ABS ring, spacer, etc., to replace the seal.

The front wheel bearings are HUGE, and are sealed double-sided tapered roller bearings, and I doubt they will ever wear out in the life of the truck, unless you submerged it for a great length of time in water.

They are sealed, here is a writeup I found that should shed some light on it. http://128.83.80.200/taco/rwb.html