Clonking on reverse turn

I'm getting a loud clonking from underneath when reversing left or right in my 2.0DI (V reg, 105k miles) - I'm assuming that my IRD is about to let go?

No noise (yet) going forward or even reversing in a straight line and otherwise all seems OK.

Any advice would be apppreciated.

Sniffer

most likely a cracked chassis, a rear subframe attachment nut broken loose or a diff mounting rubber bush.

My rear offsided subframe mount went last year and I had it sorted - this is way louder and sounds to be coming from the front of the car (just about where the IRD is!)