Strictly speaking it was yesterday but I changed the oil in the final drive units. Rear wasn't bad but the front was a grey emulsion. No sign of oil getting past the seals and the breather is fine yet it looks like water got in. I have done a lot of wading this winter. Looks like that might explain the noisy front diff. Unfortunately it has got quieter with new oil but still whining.
Give it a fortnight and change again, was there much silver dust in the slime ?