T350 random clonk!

[monty quick]

I know it is a long shot but worth asking in case someone says 'I had that and it was.....'

Every now and then I hear a dull metalic clonk - loud enough to hear clearly over my ACT exhaust. The noise is the same irrespective of enging revs or road speed. Possibly most common at low speeds. I thought engine mounts / exhaust ???? but I can't find anything that moves enough for me to believe it could make this noise.

[monty quick]

I think we can discount diff - the noise doesn't seem to be load or cornering dependant.
Fuel tank? Please expand - could the tank be moving?
Any other suggestions?
Thanks

[monty quick]

I have been out of the country a couple of weeks but, if the storms allow, I will have a good look this weekend.