2008 Tacoma Prerunner TRD rear bearings?

My 2008 with 124k miles has some bearings in the rear end that have been making noise for a long time. It isnt so loud that you'd immediately know something is wrong upon driving or riding in the truck, but when I had a seal replaced last month, my mechanic asked me how long my bearings had been making the noise.

I was confused since the noise has happened for quite some time and I honestly thought it was just road noise. It literally sounds like worn tires sound when you drive with them like that. I should have known better since I have new Michelin LTX-MS tires that are quiet as a mouse.

Anyways, the truck runs fine, but now that I know about the issue, it is driving me crazy and I want it fixed. I am wondering how many different bearings are there to potentially replace?

Seems it could be the actual gearbox in the rear end as well as behind each wheel. Anyone have any insight?