Whining noise when decelerating from high speeds

Hi,

This is most likely a bearing noise. Normally when it only makes on deceleration it is something related to the drive shaft or drive gear bearings in the rear. If you are sure it is coming from the front then it could be a wheel bearing. However, these normally don't go away when accelerating.

Is this loud enough to get on a recording? If so, please post a video of it so I can hear it.

Also, the way to confirm it is not the driveshaft is to remove the rear shaft and put it in 4 high and drive the vehicle to see if the noise is gone. Clearly with your noise being a higher speeds you will want to do this in a safe place. Somewhere you can get up to that speed easily with out having to drive a long distance. Thanks

https://www.2carpros.com/articles/whirring-sound

So far unable to capture the noise on video. After reading your response I did look at the rear differential housing. Looks like the gasket may be seeping. There are no puddles under the car so not a leak. Would this possibly have something to do with it?

Also have determined that the whine stops if I put it in neutral.

It very well could. The unfortunate thing is if this is the pinion bearing the only way to fix it is to replace it. The symptoms that you are stating all point to a pinion issue. Basically what happens is when you are decelerating or shifting to neutral is removing the torque from the drive-train and the pinion bearing actually relaxes and starting whining.