Unfortunately I cannot compete in the high mileage however I feel its worth a mention. I always kept track of my mileage for work and had a good idea what I was getting for fuel economy so in noticed when my odometer slowed down(Feb.2002) and quit working before 400,000km. I already had the manual glow plug switch and high idle It was not long after that I had my injection pump and injectors rebuilt. In 1998 I had put new glow plugs in before I figured it was the relay problem. Since the rebuild in 02 this truck has been great and have calculated over a million kms since I bought this truck new.A few years ago I actually put the original glow plugs back in. However ,this fall while driving it surged after pulling away from a stop, then once more and then died. Still hopeful I can figure out the problem because it ran so nice up to that point