Strange noise coming from the rear of my VZ

[swift85]

Has any one got any ideas on a strange noise that i am getting coming from the rear of my VZ wagon V6.
I know it's hard to describe in writting but here goes it is a ro tating noise and increases in volume when i take foot of the accelerator.
I think it's either the diff or maybe a uni joint over a few months it's getting louder.
Has anyone had this problem.
Thanks

[Exidor]

Diff whine?
Check and change the diff oil.

[PaulSV6]

Check the mounting bolts??

[danja]

Check this thread:
Diff noise " cyclic knock " a Holden Service Issues

See if that describes what you're experiencing.