Help with troubleshooting loud hum from front driver side wheel

My 4x4 2007 Tacoma has developed a loud pulsating hum from the left drivers side wheel. Mechanics have not been able to address it. It started when I got a tire rotation. I switched the tires around and the hum continued from that front left wheel. I got the alignment rechecked. It was still good. I decided it was the bearings so I installed a new hub assembly. The noise continued. I was told that sometimes the hub assembly comes from the factory faulty. So I installed another one. Still sound. The sound becomes more deafening the faster I go. It can’t be the tires because the other tires are quiet, even after rotating them. Any ideas? I am at a complete loss. I will take your comments. Thank you.

 

Needle bearing failure? Does it go away if you pop it in 4wd?

 

It does not go away when I put it into 4 wheel drive. I did try that. Hmmm...needle bearing. I will look that up. Thank you