Okay, I can now say beyond any doubt that it is not really practical to replace the bearings alone.
First off: I will call the whole part the "hub assembly". The part that spins is the actual
hub, and the part that bolts to the truck's suspension with 3 bolts is the
bearing carrier.
To remove the hub from the bearing carrier (as well as get them back together) you need an H-frame hydraulic press and a few other bits--some chain big enough to fit the bolt through, and I also used a quick-link but if the bolts were long enough you might not need that. I also bought three m12x1.75x35 bolts to screw into the bearing carrier mount holes, to hang it by. Smaller bolts would work (with nuts + washers on the ends) but might have chewed up the hole threads, and at this point I was still being careful not to totally ruin the hub itself.
The reason you need to hang it is because the hub is the same diameter as the mount flanges on the bearing carrier. There's no way to just prop up the bearing carrier and push the hub out. I thought about cutting a triangle-shaped hole in a sheet of 1/2"-thick steel and using that, but this way (with the chain) is a lot cheaper and faster.
Once you get it
apart, pushing the thing back together is easy.
Pic #1 below should show how the hub was hung around the press:
Pic #2 below is me trying to better show how I had the chain rigged up. Since there's only three mounting holes on the bearing carrier to hang it by, using a quick-link allows getting both chain lengts the same. If you ever use this method to get anything apart, you REALLY want to try to get your piece hanging as level as you can, since when you start cranking the ram down on it the part it will try to pop out from under the ram.
Pic #3 below: I used a 32mm socket to push the hub out, as the end of the ram was too big. Also you see here, the piece tried to pop out, like I warned above (I started with it lined up perfectly straight & level...). It didn't take a huge amount of force, about 1000 lbs to crack it loose and then 150-200 lbs every time I cranked the pump handle after that. When it's pushed about halfway out, the hub falls completely free.
Pic #4 below: at last, the mysteries are revealed!!!!! Well, okay, maybe not a lot of mystery... I kinda expected tapered roller bearings since that's what all the rear wheels use, but its axial-load ball bearings instead. The hub has a separate bearing race pressed onto it, though I didn't bother to take that off (the gold ring is the bearing race). The other, bearing inner race (on the right side of the photo) is the inside one. I also popped one of the balls out for the pic (green arrow). The notched ring is the ABS sensor thingy (?) an aluminum ring pressed on to the inner race.
Pic #5 below shows why you cannot simply buy separate bearings and replace them yourself. The bearing carrier is rotated around and a bit of the crusty grease is wiped off, and here we can see that the bearing races inside the bearing carrier are cut
directly into the carrier. There is no separate race there you could replace, so you'd need to buy a whole new bearing carrier anyway. (you can go buy new ball bearings in every size there is, but if the bearing races are still munched up, the new balls aren't going to last long anyway----so you must replace both the bearings and the races)
ALL RIGHT EVERYBODY, CALM DOWN NOW.
This is pretty exciting stuff I know, but control yourselves.
I will probably wipe this out and push it back together.
It still rolls easily, just a touch of grittiness--so it may find use in some other odd thing I build, but it won't be going back on to any vehicles.
Also--if you care at all about these photos, save them. They will not be posted on my web-page forever.......
[EDIT ADDED]
Below: while wiping the thing out and discarding a few unneeded parts (the wasted grease seals) I noticed that a couple of the bearings looked odd-
These are .405" or 10.4mm diameter, and the chipped ones were on the outside of the hub. The others may look like they have little holes, but they don't, that's just junk on them. All the others looked fine except these two that had chipped heavily.
Also,,,, I don't know what brand this hub is. I already had the front left hub assembly replaced once at an independent shop, maybe 3-4 years ago.