Rear wheel bearing question

I have a 2000 Tundra with about 250k miles. I've been pulling a camper that weighs in around 5000lbs. The truck has started making some noise from the rear when accelerating to highway speeds from 30mph or so. I jacked it up and found it to be the wheel bearings.

I went ahead and drained the diff and found some metal bits in there! @$%^ Thankfully I have a low mileage donor truck, so I pulled the axles and was going to swap them out. When I found the passenger side was like new but the drivers side was very stiff. The vehicle had been sitting awhile... After a closer inspection I noticed the bearing/backing plate was nearly flush, not like the others they were recessed about a 1/4in. I fiddled around and was able to pull the backing plate up which recessed the bearing. I flipped the axle over and spun it. It was smooth as the other side. I don't know what is causing this to occur.

If I grab the backing plate and place my thumps on the bearing I can slide the whole backing plate up on the bearing 1/4in, to where it spins smooth and looks like the rest when I let go it falls back down.

On a side note I've pulled the diff to inspect too. It has no noticeable wear or markings on the pinion or ring gear. The bearings feels fine by hand.

 

Pics?

 

Here's a pic of mine when I had it out (disregard the 5mm drawing at the top, that was germane to the discussion we were having at the time). Are you saying the bearing is flush with this area of the hub?

 

I failed uploading my pics the first time they are up now. Thank you

 

ehhh it isn't a big deal, but I'll say you should
Probably change all that while you're in there.

but if not. Just tap the bearing down gently.

 

Is it missing the snap ring?

 

First picture seems to have the snap ring in place.

 

Thxs for all of the replies.

I should certainly change it all it while I'm in there no doubt! My stubbornness says I have to at least give it a go. I'd like to reuse as much of the parts trucks as I can and if I have to redo it again the right way again "soon" that is ok by me.

When I get home from work tomorrow I'll take a video of the movement and try tapping the bearing down gently.

The snap ring is in place, I took a close look to ensure it was seated well in the groove.

 

Ah, I see it now. The bearing retainer is not pressed far enough. It’s letting the bearing float in the housing.