Hi mate. First thing i did was remove the drain plug in the ird box. Not easy. The oil was clean with only minor metal sludge on the drain plug magnet. I shone a torch into the ird box and rotated and looked at the teeth which seemed ok. Apparantly they get badly damaged if viscous is ko. So filled with new oil. The bearings had gone on the viscous coupling carrier and since the old girl had done over 90k i purchased a recon vc along with new carrier bearings from bell eng. Easy to remove. New one came promptly and running ok ever since. Think secret is get vc replced before it buggers the ird box. Did run it in mondeo mode for a week. I heard that you can make do like this permanantly but there is nothing like 4wd when the going gets rough. Hope its of some help. butty