Creaking noise from rear end.

[spannerrash]

That's the car's rear end not mine by the way.

Audi S8 d2 2002

The rear end of my car creaks when going over speed bumps, even slowly. I realise there are multiple reasons why this may be happening but are there any common culprits?

I understand the rear bushes etc are not that prone to wear, well not as much as the fronts anyhow so I was thinking the spring mounts? The rubber discs that fit bellow and above the springs (not sure what the proper name is).

Any suggestions welcome.