I have never heard a noise like this in a car! It sounds like a garage door spring unwinding. Is on driver's side with no LSD.
Below is a link to the particular sound. Yes, I know I need a fan clutch too. You can tell it goes away when accelerating but comes back when constant speed or decelerating, which leads me to (ew) CV joint, but I'm just too damn stubborn to accept that.
I have isolated it to my driver's side rear. Have replaced brake pads, calipers, rotors, parking brake; they needed it anyways. Even swapped tires to check.
Anyone ever heard this particular noise?