Replacing bearings in rear end?

[Dante04SRT]

I've had a groaning sound coming from the rear diff for a WHILE now; It starts about 60mph and is accompanied by a vibration. I thought it was originally the driveshaft but after having it rebuilt, the problem is the exact same.

I changed the fluid in the rear diff a few weeks ago and everything --looked-- ok, but I'm still convinced that something is wrong. I get a nice "clunk" sound from the rear when the truck shifts 1-2 and 2-3; Definitely sounds like the pinion is moving somewhat. When I had the bed off, I was able to watch the pinion for movement while driving and couldn't see any, but it sure feels like that's what it is.

Anyway, what all is involved in replacing ANY/ALL bearings in the rear end? I assume the axle bearings can be done relatively easily with the truck on the ground (or at least on a jack stand)? How about the pinion bearing; How hard is this job? I've always been leery of pinion bearings because of setting backlash/preload/etc.

Any help would be great. Is this a job a better than average shadetree mechanic can do or is it best left to a shop?