Dodge is the only one of the three diesel trucks below class 4 to allow an exhaust brake installed without threatening warranties, that is on manual transmissions. 2 years ago, Cummins said fine use a Jacobs exhaust brake on the auto tranny too with the Dodge 2500/3500 Cummins. But Dodge drug it's feet until now. The rest of the story at www.mrtruck.net/jacobsdodge.htm