I have a 200tdi 90 with about 140k on the clock, which has developed a rumbling sound when backing off the throttle, particularly at motorway type speeds in 4th and 5th. Performance doesn't appear to be particularly affected, but as I suspect it sounds to originate somewhere gearbox-ish I'm a little concerned. Has anyone else had a similar noise? I'm hoping it might be a bearing of some description, rather than the gearbox or transfer box itself? Any help would be greatly appreciated! Thanks!