This Freelander has a groaning noise from underneath. It`s not related to engine speed but is related to wheel speed. Not affected by whether in neutral or clutch engaged or not engaged. Doesn`t seem to be related to wheel bearing. I emptied the oil out of the IRD and it was quite gunky. Lots of swarf on the drain plug. New oil seems to have made the noise worse.
I think the IRD is failing any suggestions.