Clicking noise from differential...

I have a 2002 M3 6 speed and while driving, I can hear a clicking noise that goes faster as the car goes faster. Sounds like a card in the spoke of a bicycle that kids put on there bikes to make that clicking noise. It doesn't matter if the car is in gear or in neutral, it still makes this noise. I have found that it is coming from the differential. It sometimes goes away when I drive long distances but it keeps coming back after the car is off and sitting for a while.

Could this be that I have low transmission fluid or does anyone think that this is a much bigger issue. Thanks for your responses.

jack the back of the car up and spin the wheels by hand. pinpoint where the sound is coming from. i had a clicking noise on mine, turned out to be loose-fitting brake pads.

I did that already and that's how I know the clicking noise is coming from the differential. And it's only when it hits a certain spot the wheel has turn because you can turn the wheel back and forth a couple inches in the same spot and you can hear it click

normally i would say it's the clutch discs in the LSD. i'd change the fluid or add some LS additive that bmw offers for the M3.
another thing since it's doing it on a certain spot in the rotation, it could be the pinion bearing. or even as simple as the thin metal plates around the input/output shafts being slightly bent in and rubbing. and then another is if it's when the car is rolling, could be the cv joints of the output axles.

Had the same problem. drain ur dif fluid, see if you have any picecs of your dif gears in it lol, thats wut happend to me... rlly hope thats not your problem

Did you change your diff oil recently? If you did, did you make sure to use fluid with LS additive? the LSD in your car needs specific fluids.