Rattle/vibrating noise from under x5

[84ap]

Hope you guys can help! Dealer couldnt!!!

I have a rattle from under my car, very slight but its there! Took it dealers they checked against another x5 on the court and agreed that there is a sound!

Got a call later saying we took that other x5 into the workshop and did a back to back test and the sound is there on both!

I think its porkies as when i was there the other x5 does not rattle!

The rattle is only there when its in park! As soon as i move it into drive/reverse the rattle has gone.

Can somebody tell me if they notice this rattle from under the front of the x5 when in park?? Is it normal? The noise dissapears whe in drive but comes back as soon as you put it back in park?

I have 3.0d se x5 e70 2007.

By the way they said the rattle is due to oil circulating in the gearbox!