From what I can tell most pickups with diesel engines do not come with exhaust brakes on them, except, I believe, for the latest iteration of the 6.7 Cummins. For those of you who have diesels, do ...
All the newer diesels have them. I waited several years to get one for mine. What a mistake! I should have put one on the first week. I tow over the passes here a lot and it's the best mod I have ever done.