2021 toyota tacoma trd off-road rear-end making noise

I don’t see any. Not unless the blocks are degreed?

But I don’t think that’s your problem. Degree shins are for vibrations not whining diffs.

 

I was just adding to your post. In my experience if the noise is under load, a bearing is done.

 

Ok noises, there fun!
Upon a drive line complaint a road test with the client is a must, so be prepared to help diagnose the problem. I suggest have someone drive wile you are in the back seat area preferably without seats, if possible. Use an old stethoscope with the end removed this acts like a directional mike. Find the area with the loudest about of noise. This should help eliminate some usual suspects. The drive shaft is a great sound amplifier so if the noise is in the middle of the floor to the back of the cab the drive shaft is your suspect. Diff noises travel up the shaft!
Divide and conquer is the way. Now check the center bearing this us usually overlooked but can howl prity good.

 

Road noise part 2
Road noise can be alot of things Tires, drive train, you name it. If you have determined there is no mechanical fault to your noise now you ask why your are hearing noises inside your cab. I own a 2021 trd sport and I am experiencing similar noise as described in this thread. Now I have narrowed it down to tire noise but I think it's too loud. Now I checked the back seat and I noticed a subwoofer, I have a premium sound system, inside a plastic enclobolted the the rear wall. I think you know where I am going with this. I am currently removing the sound box and insulate the mounts and apply insulation to the rear wall I am using matt I will post a link and it works great I side the doors as well. I will be installing insulation in all the doors.