When differentials fail in Range Rovers, they tend to fail in front. Over the years we have changed 3-4 times as many front as rear differentials. I'm not sure why that is, as the same part is used front and rear. Some say it's because of the traction control. Others suggest the front does more work because those are the steered wheels.
We recently had a 2006 Sport differential fail, at 75,000 miles. The truck had Mobil 1 gear lub all its life, changed at 15 and 45k miles, yet the bearings came apart as you can see.
I wish I knew what we might do to avoid repeat failures, but I don't. For now, we fit the factory replacements and hope for a preventative answer