Thanks guys and gals. No not wanting to 'hijack a thread' however I do not also want to start an unnecessary thread
Took the FIL for a drive today, whom has owned multiple Jeeps with 4WD and full time 4WD today and he didn't notice anything untoward.
Being a mechanical engineer it is telling me something is amis... out of balance shaft, something....
47K service coming up soon so I shall see then.