2004 Dodge Ram 3500, 5.9 (6 cyl) Cummins Turbo Diesel. Just about at 160K miles. I had valves adjusted at 100K, otherwise nothing but oil/fuel filter changes done annually. I switched to a larger area, reuseable, air filter. I use Diesel Power Plus fuel additive continuously, and added an EGT gauge that I keep below 1200 degrees. I also run the engine for a couple of minutes when shutting down, getting the EGT to below 400 degrees (to prevent turbo oil coking).
On edit: I met another RAM 3500 dually diesel owner at a gas station near Stockton, Ca. a couple of year ago, who had a gooseneck car hauler trailer and said that he contracted with car rental companies to move cars around between rental locations. This guy said that he had 1 MILLION Miles on his truck with NO DRIVETRAIN REPAIRS!!!