please help. I can't figure out what I am missing.

2008 dodge 3500 4x4 6.7L.

wheel bearing blew out while driving. My first thought was I didn't hear it grinding out and let it go too long. Basically whole wheel fell out with caliper only thing holding it on.
i go to salvage yard and get another for a quick fix so that I can order a new pair online. Install the used bearing spindle. Make it 3 miles down the road and same thing, it like king king grabbed the wheel and yanked the guts right out of the bearing assembly and pulled wheel off. So I think I just bought a bad one. I go to auto parts store and buy a overpriced new one. Install it, and 3 miles down the road the same thing. Guts ripped right out of bearing.
Now looking at it, you wonder what it is that holds the bearing together. Sure one side mounts to truck with 4 bolts, and other side mounts to wheel, but what hold the two sides together in the middle. It's just the bearing itself which clearly isn't very strong. What am I missing? I have looked at every diagram and see nothing missing.

 

The nut on the end of the axle is what holds it all together. They get torqued to some truly stupid value. If the nut isn't torqued to spec, the bearing will waste itself in pretty short order.

 

Well, I pulled the 4x4 axle out 5 months ago and it's just been a 2 wheel drive since then. The axle just slides out so I didn't see where it was actually holding anything together. How was I able to drive and tow over the past 5 months and nothing happened? And nothing is happening to the other side.? It makes sense. But differential gears are chewed up and I needed to drive it. Was told it would just be a 2x4 and nothing more is changed

 

I haven't had a nut on either side since I pulled those axles out 5-6 months ago.
could alignment be causing it. Wheels look straight, and drives straight with hands off the wheel.
Or have I just been lucky for 6 months that they have held together. That just doesn't seem possible with the amount of weight. And this is a tow truck. So i tow without those nuts one either end holding the axle in place.
scratching head

 

You have just been lucky.

If you don't want to fix the front diff, for whatever reason, pull the shaft out of the outer CV joint, and just bolt that in place. That will hold the bearing together.

 

Ok. That's the part I was wondering about. Looking at a new bearing in hand, I couldn't wrap my brain around how that would hold together. But had been for so long.
Thank you very much for your help.

 

Luck plays a role in your day to day life. I think you burned a BUNCH of it over those several months.

 

Yeah, I have had ****ty luck everyday for a long time. I guess it's because it was all being used on those bearings.
now that I look at that joint, I don't know how I could be so stupid. I was just told that it wasn't needed and didn't investigate anymore myself.
byt it's obvious by looking at it, that it's 100% necessary.