Does any PERFORMANCE MODS ON THE ENGINE? With TODAYS electronically CONTROLLED Diesels, more hp is just a plug in! Does he have an ehxaust brake? The performance mods could change his engine governed speed. He could be over-revving it. If the ehxaust brake restricts too much and the guy didn't have heavier ehxaust valve springs installed, A valve can stay hung open and get hit by the piston. This was an issue with earlier, 12valve Cummins diesels in Dodge trucks.
This guy sounds like he just hasn't suffered enough in the pocketbook yet to take his RIGHT foot off the floorboard!!!

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My Truck.. 2007 DODGE, 5.9 Cummins, 6spd stick, 4X4. My car..1977 240D, OTHER WHEELS...1955 VW Oval window bug, European Delivery (Holland) with a 1700cc, 2 barrel, Porsche drum brakes. 1939 WILLYS Pick-up. 1967 Triumph 200cc Tiger Cub. 1976 Honda 550F 4cyl Motor Cycle.