Need Help Figuring Out Mystery Noise!

First time posting so I apologize if this has been covered before. I have a 2012 Tacoma PreRunner 4cyl 2.7 Rear Wheel Drive that when im accelerating downhill makes a high pitch whistle/rubbing noise only at 55-65mph. It only does this downhill and while the gas pedal is pressed and only at that certain speed. If I let off the gas the noise goes away immediately. And if im going thay speed on flat roads or uphill theres no noise. Anybody have any ideas? Thanks in advance!

 

auto or manual

 

grease your U joints...then see

 

Auto

 

might possibly the air just rushing around whistling. Mine does that crossing the Straits of Mackinaw on a windy day...look up kazoo tacaoma and see if that is what youre hearing

 

Check the exhaust heat shield mounted to the floor above the cat is secure

 

Lots of things it can be at this point. Might need to wait for the noise to worsen. First things that came to mind were the fan clutch and a pulley bearing.

 

Yep, do this first