Noise coming from rear only during acceleration

[ellicitcs]

I have a 2017 X5 sDrive35i with 34K I've been noticing an odd noise coming from the rear which only during acceleration, it doesn't seem to be a suspension problem since there is nothing when I go over bumps, turn hard, or when I go over speed bumps. My concern is it could transfer case, being that I have a sDrive (RWD) do I even have a transfer case? I did look into the symptoms I have not power lost spins or the sound profile that a bad transfer case would makes.

Any suggestion on what it could be or where to look?

[Ascotgrun]

No transfer case on S drive. Try to give more detail on the noise. Is it a clunking, rubbing, whining noise?. Under light, moderate or hard acceleration?. Any signs of leaks from the differential or transmission?.