While driving on the interstate at 75mph the vehicle shutdown and would not allow a restart. I had to coast over to the emergency lane with no engine power. Once stopped the vehicle would not start. After having the vehicle hauled to the dealership I was informed that the engine had locked-up and a new engine would have to be ordered and replace the engine. The dealership could not provide me with a repair date because they said GMC has lots of problems with this engine and it would be backordered.