I put approx. 15,000 per year and usually trade them at under 80,000 miles. I know most of the time I will be under warranty but breakdowns are still a major aggregation, especially if it's your only vehicle.
It is doubtful you will have any negative issues with any of the big three diesels in 80,000 miles. As an aside I have owned three Rams with the Cummins and the engine breaks in nicely around 80-85,000 miles and picks up an extra mile or two per gallon. Nationwide, a few Cummins/Rams have made two million miles without the engine being taken apart and others have exceeded one million. 80,000 miles is nothing on any of the big three diesels. But what you get in towing abillity with a diesel is almost everything. I would not be afraid of any DEF engine as ammonia (cow pee) is introduced downstream from the engine into the exhaust. It probably adds a tenth of a cent per operating mile and some of that is recouped in slightly better fuel economy.
