Has started to get a bit louder recently, thought it was a wheel bearing, jacked it up and there is a noise when spinning either rear wheel, this noise only comes on when lift of the accelerator and I'm positive it's from the rear, it goes away a little if I drop into neutral but doesn't disappear, could it be the diff, mileage is 90k, any help or advice welcome

I think RRSTDV8 had i similiar noise from the rear diff, he had his replaced. I'm sure he will be along soon to give his imput.

Thanks also got a bit of clonk when I brake sometimes, just done all arb bushes which has solved most of my noises but still this one?

I had similar noise plus vibrating through the steering wheel turned out to be the front diff.

It was only really noticeable after 30mph on wards when lifting off the accelerator. Did exactly what you did jacked it up and spun the wheel the whirring noise was still there coming from the diff.

What's the best way to determine if its front or rear diff then?

Chassisear kit, or drain the diffs, and check the condition of the oil.

Should be pretty apparent which diff is faulty, by condition/colour of the oil

Not sure I can add much. Mine was dealt with by the dealer under warranty. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed