Here's what I have and searching sort of got me in the right direction but maybe someone has had this exact issue before and might be able to diagnose which bearing(s) are bad.

1996 Dodge Ram 2WD, Open Differential (I confirmed that from the build sheet and also by testing it with a few brake-stands, it only ever spins one tire in a straight line).

What I have is definitely a bearing noise (Like a howling noise maybe or other high-pitched sound).

This happens only under load I can only hear it at about 25-30mph below that I can't hear it (this is with the sliding rear window open). It becomes louder with speed until you hit highway speed then the wind noise blocks it out (you can still hear it if you listen carefully).

Also, I had it up on the hoist and when I spin the tires by hand with the trans in neutral the Drivers side spins freely, the Passenger side has a stiff spot in it where it rotate freely then there is significant resistance in one spot that you have to get by. Once past than then it spins freely again until it hits that stiff spot again.

The brakes work without any locking up or sticking so it's not that the drum is out of round or something like that.

I have tried in probably nauseating detail to explain this, my thought is if only one side is showing this resistance than the problem is with a bearing only on that side of the axle (I would not suspect the "Front Bearing", the one that is closest to the driveshaft entry point).

So from the service manual that leaves either the Differential or Axle Shaft bearing (maybe both)?

I am going to pull the cover off this week and at least get the Fluid changed at which time I can inspect what it looks like in there.

There's approximately 250k miles on it (403km) so I may have a failure of something that may not typically fail given the mileage on it.

I'm also considering if I'm going to have to take the entire assembly apart just buying another lower mileage assembly and swapping the entire thing in.

Again sorry for the length of this if you can think of any other questions to diagnose let me know.

 

you have 3 sets of bearings in the rear.
pinion bearing
carrier bearings (at the diff).
rear axle bearings out at the end of the axle tubes.

pinion bearing will sometimes roar on acceleration and growl on decelleration.
carrier and axle is usually a more steady roar or ring.

put it up on jack stands and pull the cover and inspect. you can even run it in gear a little bit with the cover off but be very careful and don't get maimed or killed.

 

Sounds more like an axle bearing to me, as I suspect when you rotate the passenger side tire, the drivers side tire rotates the other way, and the driveshaft is stationary..... thus, the carrier bearings aren't moving.

 

Yes, the other wheel rotates the other way which I guess is another way to confirm an Open differential.

It will be more clear once I get the cover off, it's possible the noise and this resistance in turning are not the same problem.

I do want to get to the bottom of it before it gets worse, such issues never improve and usually cause other problems over time.

 

I figured I'd update this in case someone had the same noise.

The noise got progressively worse to the point I could hear it clearly over the exhaust (this with a Cherry Bomb dumped right behind the cab before the axle).

So I got a friend that's good with differential work to take it apart and replace all the bearings. There's no way I would have attempted this myself. You need a special tool to get at either end of the carrier, then you have to understand terms like backlash, pinion depth and preload!

In any case the carrier and all the gears/axles looked good the gear oil was pretty old and stinky though. We couldn't determine which bearing was bad they looked good, the only issue I had was a small leak from the pinion seal.

There wasn't any metal pieces on the magnet and for a truck with as many miles on it as this one has it didn't look worn out at all.

I also replaced the U-joint on the axle side as it didn't look great and since it was disconnected why not.

So after putting it all back together the noise is gone. It was certainly something in the differential, it might have only needed some new oil but with the pinion seal leaking it likely would have had to come apart anyways.

I did learn without having tried it myself to leave the differential stuff to someone who knows what they are doing.

 

Gear Oil stinks to high hell!!! Worse than hot transmission fluid....

Glad you got it resolved

 

I didn't find the fresh stuff all that bad, the old stuff in the truck smelled like dead fish, I made sure not to get that on anything I planned to wear ever again!

Next up is to decide if I'm going to put air bags on the rear leafs or add a leaf in to the existing ones (the truck has a bad rearward lean since I got the Coil springs replaced on it). Like I have a load in the back when I don't.

 

Go air-bags they work great and will not make the truck ride hard. But that is just a cover up for sagging rear springs, got any spring shops in your area? If yes they can re-arc the springs back to factory specs and/or replace one leaf spring for you.