2004 LR Disco2 SE7 4.6L

I have been looking at previous threads and the high pitch noise seems to be common at a certain speed while mine is at a specific RPM.

No matter how hard I step on the gas, I can still hear it when I come accross 1700 RPM.

I thought it was related to my P0705 issue but the XYZ sensor replacement did not fix that part. However, the used module (95$ on ebay) from Texas did fix my limp mode problem.

Any ideas where to head or where to look for the noise?

Another thing which is on my mind is doing a partial flush on transmission fluids (drain and fill without opening the transmission oil pan and replacing the filter). Fluids have never been replaced and the truck currently has 97 000 miles.