I love my B5.9 uprated to 300 hp. It is 12 MPG at about 65. I stay pretty steady on all but the larger grades. My Allison MD3060 has ran flawlessly except for an ECU hiccup last summer. The old 12 valves are the king of the cummins small 6's and I have seen many built to over 1000 HP and about that much torque. There have for sure been many innovations over the years but I am not sure all the innovation was for the better. Common rail fuel injection did quiet them down but I did not see the fuel mileage increase with them. The so called advancements have added a great deal of cost along with in some cases lesser MPG. Any Diesel should get you into the 500,000 mile longevity range and beyond.
