Rust/dents = improper usage, operator error
Look at the aviation industry, people still fly in planes built in the 50s and 60s, and those planes are better then when they were new... how on earth could this be you ask?
First of all you have to have you ac inspected,
it's not like a truck where you can drive it on 3 or 8 cylinders and diffrent size tires and only have to worry about having a bad ride.
They take care of them, rubbing glycerin jell on the rubber of your truck makes the rubber last longer.
POR15 (or similar) the un-coated areas of your sheet metal eliminates the rust (if done properly)
CLEANNESS IS GODLINESS, if you clean your truck you can prevent rust even on a truck that is not properly undercoated, not to mention while cleaning your undercarriage you are going to find problems EARLIER as you will be in the habit of knowing the EXACT way everything looks under there!
A mechanical device will last until the end of time if proper care is taken