W210 odd clanking sound, help please

[crostonian]

Hi, my 1999 E320 CDi Auto saloon makes a very loud clanking sound on deceleration, it sounds like someone is smacking a metal tray against the floorpan, the frequency is speed related. We've had it up on the ramp and nothing is obvious, it seems to be coming from the rear of the car. At first I thought it was a loose heat shield but all are fine - it's loud enough for pedestrians to turn round 100 yards away. Anyone got any ideas, I'm putting it up for sale soon and would like to get it sorted.

[rangie999]

Sounds like a differential mount but not sure as that would also move on acceleration? Interesting problem. Maybe look further up the drivetrain to gearbox mounting as the noise can travel on these things. I spent a while thinking I needed a new diff as it was very noisy. This was accepted by a couple of garages as being the likely fault. During my deliberations I had a third opinion and he suggested the noise was a wheel bearing at the front!. Turns out it was the wheel bearing in the end but had me and a couple of experts foxed for a while!