99 Toyota Tacoma Prerunner rear end noise?

I have 2 possibly related things going on.

1)My truck has had an intermittent squealing noise from the rear for years now. It only seems to happen at neutral throttle and at 30-70 mph. It goes away when the chassis attitude changes, ie when acceleration or deceleration changes the body angle a little. Brakes have been done several times over the years with no change on the sound.

It sounds like rubber rubbing on something, but looking around under there I can’t really see anything that seems to be a likely source.

I’ve always suspected that it was related to a carrier bearing, but if one was failing it would have happened in the 100000 miles I have driven it, right?

2) It shakes at 60-65 mph, I’ve been stalling on a 4 wheel alignment forever. Think that would help the shake at least? It changed a little when I had tires rotated, so I had them all balanced again but it continues. The tires wear funky from it, but since most of my driving is city I don’t really think of it too often.

When you were under the vehicle looking, did you try manually shaking things looking for any worn busings? Did you use a good work light and look closely at all the articulated joints (sway bar links, spring mounts, etc.)?

Forgot to say that there is 125,000 miles on the truck.

Yeah, I’ve poked and prodded around under there many times. I’ve never been able to reproduce it, but I’ve never been able to spin the wheels or drive shaft to check that out. I was just messing with it today and there is a squeak in the suspension, so it is possible that is the source; but it doesn’t really sound the same. It is hard to tell for sure since I’ve only heard the squeal with road noise mixed in.

Like you I can’t imagine a sqeaky carrier bearing lasting through years of wear without deteriorating into a clunky assemblage of worn out parts. But unless there were signs of leakage at the pinion shaft or some tell-tale sign of that sort I’m stumped as to what to suggest.

If it were a whining sound I’d suggest inspecting for abnormal wear on the crown (ring) gear in the differential, but as with the carrier bearing I’d expect that to get worse over time.

Thanks for the help. I know it is a difficult issue to try to diagnose online
What else can I add to this that might help—

Seems to be only in cool to cold weather, usually also when it’s wet.

If I compress the suspension and release there is a squeak, maybe I am just hearing that squeak repeated rapidly as the suspension does its thing? So maybe I need to look mare carefully at bushings and rubber boots and the like. Are suspension squeaks usually bushings?

Whatever makes the noise, it doesn’t seem to have really hurt anything, and at this mileage failed bearings and worn out rubber pieces are likely anyway. I should just consider myself lucky that it has been a good truck and continue to ignore it.

Try liberally squirting some silicone lube on the joint in question and see if that helps. It won’t harm rubber bushings either, so it could actually be used on all the bushinged joints while you’re there.