2008 Tundra Crewmax Limited Loud at 55-65 mph

I'm new to the forum but am very excited to have my first truck. I bought a 2008 Tundra Crewmax Limited with 92,000 on it. I absolutely love the truck but can't figure out the noise I hear from behind me when going 55-65 mph. It's a loud humming noise. I took it in to the local shop to have them check it out. The brakes are new and they said it's not the wheel bearings. They said it needs a new exhaust but I'm not convinced. It's only at 55-65 mph and only when I put my foot on the accelerator pedal. I saw another thread where someone mentioned a resonator. Anyone have any ideas on what it might be?

 

You have a small exhaust leak in your pipes. Crawl under and look for signs of exhaust leaks.

 

Welcome from NorCal!

I know you stated it’s a humming sound but could it be also described as a high pitch whining? Some rear differentials can whine at a specific speed.

Is there any vibration that accompanies the sound?