My '02 cargo van has 120k miles on it, not a mechanical failure to speak of. It's only been on a hook once and that was from a high speed collision with a big pregnant elk.
A splash of Gunk diesel conditioner with every tank of fuel seems to go a long way. Oil changed every 7500 miles, uses about a quart between oil changes and has since the day it was new.
The '97 it replaced is sold but still running hard at 600,000 miles, the last 150-200k of which it's been pulling heavy trailer loads alot of the time. It finally had the tranny and injector pump replaced earlier this year when it was closer to 500k miles. Otherwise it's gone through a couple of turbo sensors, an injector pump module, two sets of brakes, a few sets of u-joints, one set of front suspension bushings, one set of shocks, one set of batteries, one starter and one alternator. No signs of rust on the body, it puffs a wee bit of blue once in a while but not worn out by any means. Might be a few things I'm leaving out but those are the major things that came to mind, anything else is too miniscule to remember. It's been on the hook once as well when the serpentine belt went at around 130k.
Both of these are always on the highway at around 60-65MPH, no hour meter but very little idle time/stop and go, average MPH is probably about 55.