Diesel Question for truck campers

I read about these 200-300 thousand mile pickups, and I am sure there are some, but.... Do these high milers come with bodies, suspension, steering, and other components to match? I have driven a lot of miles in pickups and never had one I enjoyed driving after about 125,000 miles. I suspect most people who drive $50-60k pickups get rid of them long before they reach triple digits, whether they are gas or diesel powered. At 15,000 miles per year, it would take twenty years to reach 300,000 miles. There are lots of reasons to own pickups, but driving the same one for twenty years is not one for me.