Outer Limits 4x4 Board

I seem to have a leak from what looks like the rear main seal when i go 4wdriving (going up steep hills!!) has this happened to any one else, and is it as simple as what it seems to fix.

Andrew

Rear main seal requires the box to be split from the engine.

Rear main seal requires the box to be split from the engine. My box spills oil from the selector whilst on steep inclines. It then makes its way south below the box and sump.