I cant figure out your picture above. I too and having the same issue. As I am driving and hit around 60 MPH I can hear this plasticy buzzing sound. I thought it sounds like it was coming from the 4wd selector switches and vent area. It's so hard to tell. But based on what you said the sound travelled. Maybe my issue is the same you are describing. However, I can't make out the picture you posted and where to find that component.