clunking gargling noise !!

[Taj Khan]

Hi, can anyone help.

For the past week when i have been driving my X5, when i put my foot down, i can hear this kind of short clunking gargling noises coming. it happens whenever i feel the auto box is about to change gear and it's getting me worried. i can't make it if it's coming from the front end (engine) or center (gearbox).

Also, do the gearboxes need servicing (oil change etc) ?

can anyone advise me what to do or how to inspect this problem further ??

Thanks