Last week while driving down the road pulling a 10,000 # trailer my engine just quit like you shut it down. There was a faint smell of diesel fuel and that's it.
I had it towed to the Chevy dealer and after some testing found the pump to be leaking, they removed it and found that a gear had seized up and the shaft sheared off and that had punched a small hole in the alum. end plate.
It's a 2003 Duramax in a 2500 HD crew cab w. 78,000 mi.
The dealer said this was rare and had only seen two previosley.