Disco II Td5 Auto vibration outcomes?

Hi
Greetings from Cape Town, South Africa!
My Disco II Td5 auto (2002 model) has developed a "rumbling vibration" between 100 and 110 km/h.
It starts when I reach 100 km/h and disappears again above 110 km/h.
It does not disappear if I take my foot off the accelerator, but only goes away once the speed drops below 100 km/h again.
I have swopped wheels with a friend, but the vibration persisted.
I have read many threads and the "usual suspects" seem to be:

• unbalanced or buckled wheels (eliminated in my case)
• un-balanced prop-shafts
• U-joints
• rubber "doughnut" at the back
• wheel bearings.

Having read the threads I found very few "final feedback/solution reports".
Can anyone give some insight as to what the outcome/solution of their problems were?
Kind regards
Danie

Welcome to the forum

Yer need to ask yer question over int Disco section where one of the welders shorry, fellow disco owners will be able to help