For whatever reason I have always believed a diesel engine should be a inline 6 instead of a v8.  My dad has a 05 duramax and has never had any problems, but I think my cummins will last longer.  You never see a v8 diesel in a semi or machinery of any kind.  I had heard that the 6.0 ford wasn't the best, tried to  get to much power out of a smaller engine.