I don't know if any one has thoughts on this one , it's a fsti its on 140 k miles , on very light throttle between 50 mph to 70 mph ish , I get a resonating drone noise it's difficult to tell if it's transfer or rear diff I don't know if it is transfer or diff I'm assuming it is , as soon as I accelerate normally it goes away , it's only there on light throttle , it does not appear to be wheel bearings , it sounds like resonating rather than worn gears , I suppose it could be early stages of a bearing failing , the diff and box appear fine noise wise when it's been driven under acceleration , I've checked out diff hanger bushes they seem OK , the rear diff bushes seem OK , any thoughts please ?

 

Any thoughts on this please ?

 

Could be the haldex pump or plates, can cause all sorts of problems, my r32 haldex unit packed in at 30k lucky was replaced on warrenty.

Id check the oil in it as if its dry it could be the plates rattling.