My Duramax has an hour meter and odometer. When the odometer was at about 100k the hour meter was about 4000hrs. My research at the time suggested the hours were a bit high for that mileage- about 25mph avg. A fire engine I saw had about 19000 miles and about 1450 hrs. Under the abuse the fire engine sees they are pulling heads for something by about 150,000-200,000 miles. They are all Detroit Diesels. A little math says they last about 10,000+ hrs with terrible treatment and good maintenance before needed a major repair. Not sure the engine or application you are wanting info for. Hopefully having hours and mileage on two diesels will provide some reference and be somewhat useful for your curiosity.