I have the Duramax/Allison combination. It is a very sloppy running engine. Sloppy in that it is not efficient at burning the $3 plus/gallon fuel it takes to run her. She smokes and run your finger on the inside of the tailpipe and you'll see what I mean. My guess is that in the hoursepower wars, GM spared no expense in trying to get ahead of the competition. They should have left the 0-60 nad quarter mile bragging rights to a more appropriate vehicle like the Camaro or Corvette. I'm looking for a new owner for this one.
I enjoy this truck. The diesel has a lot of pep. The manual trans. is nice after getting a feel for it. The build quality for my W/T is less than desired. Handling is excellent for a truck this size. Ride is smooth. It has some design faults (ex: windshield wipers rise only about 3" from glass, pain to work on) and penny pinching faults (ex: no sun tint on top of windshield). All in all, I recommend.