So I know there’s going to be a little whine and it’s normal that’s not the whine I’m talking about. This is like a grinding whine at the same time. It’s weird any ideas I have the video. It’s only in first when accelerating and decelerating. First works fine tho and so do all other gears. The go into each smoothly and without a problem. Could it be the diff? In the video you can hear it in second a little if I’m hearing it right but nothing like first.

 

Does it have a different final drive that was installed into the rear diff? If installed improperly the whine can be quite noticeable. Change out the rear diff fluid and see if that helps, could be low or not have the correct fluid as well.