Symptoms of rear end going bad?

When I had my 88 and 94 Toyota, I could always tell when the diff was going, just a sound you get use to. I beat the HELL outta both of those trucks and expected repairs to be often.

I will say one thing that back then, no one seemed t understand. The vents on these diffs plug up very easily, then the oil goes out the front seal, low on oil and the diff finally blows...

I drill them out on my lathe and run a hose up into the frame for them.

MANY diffs have blown due to this one simple "one-way-valve" on the diff itself...

 

My 2000 PreRunner had random squeaking on decel and sometimes accel and it was the center support bearing of the two piece driveshaft. Easy peasy.

 

jesus. What is that, like 40 pounds of wire in there?!

 

Went to a drivetrain shop and explained to to him and asked his opinion, he didn't have time to jack it up and look at it.
From what I described he seemed to think it could be a shim on the spider gears that is getting eaten up, he said he doubted the actual gears are messed up because I would probably hear/feel that driving. His suggestion was to pull the drain plug again in a week or so and see if more metal is on it.
Basically without having the third pulled he said he couldn't say for sure what it is, so I'm thinking of pulling the third myself and taking it in and having it inspected by him, he said it'd only be like $50 for him to inspect and figure out what's wrong once it's out of the truck

 

That valve is on the left top of the drivers side of the diff/3rd member.

If you take it apart (it's peened over in OEM form), you need a screwdriver to "un-peen" it. Inside, you will find the I.D. will have rust and corrosion in it, and that's what I drill out a bit larger without harming the strength of the valve. Doesn't have to be super tight anyhow...

Inside, one the thin cover/cap is removed, you will find a spring and a flat rubber discs. It ONLY allows air out, not bake in. It does not require fresh air as that fluid splashes all around from LH axle seal to RH axle seal.

Once I started taking them apart and cleaning them, I realized that there was still an issue. So I spun it on my lathe for 3o seconds and made a nub that I could put a hose on it up into my frame, nice and high. And anytime you run a drain/overflow type hose, you should split the hose at the end so it cannot plug up. All I have and will ever own are Toyota trucks, so I run a hose on all of them...

I grease and inspect my driveshafts with every oil change as well. You can visually and physically check those out pretty easy...

 

Ring gear/gears look ok from pic , E-lockers aren't as strong as I once thought

 

I noticed a similar squeaking/squealing noise on my truck about a week ago. Only hear it when I put in the clutch/put it in neutral or when I’m going downhill and there’s no load. Starts around 15mph and gets progressively louder but not too much louder. My thoughts were carrier bearing or u joints, anyone else?

Sounds almost exactly like this, except the noise goes away when I step on the gas pedal and put some load on.
https://youtu.be/SILhDmdTlRY

 

Sounds like the pinion gear dust cover or similar...