Hello
The noise that I think that you may be hearing is a normal noise from the transfer gears in the transmission, the angle of the cut on the gears makes a whine/howl/whistle type noise, normally this noise is slightly louder when coasting with little to no throttle input, some cars are louder than others
If you have no check engine light and no codes in the computers and your fluid is full and clean, red to pink in color no burnt smell and the car is shifting nicely and strong then this is most likely what you are hearing, if the fluid is burnt you should have the pan removed and inspected for foreign material or derbies, if found you may have the start of internal problem, but normally the check engine light will be on and the car will not shift right or not at all at this point
I hope that this helps you
If you need more information or help just let me know
Thank you
Donny
ASE Certified Technician
A.S.E. Master Technician, Over 25 years working in Chrysler dealers, Top tech DaimlerChrysler 1998