Rear End Noise

The diff howl is also normal in my perception (now), but that's because I know it's fairly widespread in these trucks and the diffs don't tend to rapidly disassemble themselves.
If one wasn't familiar with these trucks and their quirks however, I'd say that noise would be somewhat concerning to someone with some general mechanical knowledge.

 

I have a 22 Off road with the whine. Toyota customer service and the service manager have really been no help just like the TSB repair. I am very disappointed that Toyota can't find a fix for this. It just keeps getting worse.

 

Have you tried a pool noodle? Strangely I am not joking

 

It might be a good idea to check the rear Diff fluid level even on a newer truck. My Tacoma transmission came one quart low from the factory.