Engine Whining noise?

A couple days ago I started my truck and noticed a whining noise that sounds like its under the cab. It whines while accelerating and then quiets down around 35mph. It whines while idling in park and neutral but isn't as loud when in drive and not moving. Any ideas?

2006 Pre-Runner 112k miles.

 

while parked or stopped does turning the wheel change the sound? could be a power steering pump?

 

No, the only thing that changes the noise is accelerating, decelerating, and shifting.

 

Sounds like the fuel pump.

 

Maybe a drive belt pulley bearing?

Does it do this with the A/C on only?

 

Alternator is another common source fro whining.

 

Alright, I took it to a garage and he said the noise is coming from the transmission. He couldn’t open it up and check it out but he said as long as it’s not slipping or driving bad to leave it. Any ideas of what it could be inside the transmission?