The 6.4L cuts deeply into the diesel TV territory. The main advantage the diesel has is pulling at highway speeds in hilly, 4% - 7% country. The 6.4L will work while the 6.7L purrs along. Acceleration and climbing in the steep mountains the 6.4L and the 6.7L are actually shoulder to shoulder. Comparing the stability of the 2013 6.7L to the 2014 6.4L there is no comparison. The 6.4l pulls a TT much better due to the five link rear suspension. I think that the diesel pulling group just moved up quite a bit. MM49