Any member managed to solve this problem ???

My 2010 RRS 3.0tdv6, 110 000 KM, started to have this issue, 20 000 KM ago.

Problem is that local garages can not find problem.
Driveshaft, prop shaft, centre bearing...all excellent.
Done tranny service, transfer box, diffs...all done.
What could be issue ?
Mostly noticeable when coasting cca 100 km/h and release/apply gas pedal, also in normal driving when gas pedal released/applied.
I thought it is transfer box chain, but after reading all posts i am not sure.
people that had chain issue could hear grinding sound (chain slipping over teethes)
Torque converter is mentioned also, but personally i do not believe that is problem.
It is locking good and up-shift/downshift/pulling without problem or vibrations

Anyone resolved/fixed this or we are all still driving with this problem ???
Thanks