Can anyone tell me why so many of the F150 I've seen on the road are loaded with rust. Is this problem pervasive to the F150?

 

What year are they, like 1940's? I see alot of F150's everyday and I live back in saltland (New Hampshire) and I have seen maybe one or two at most in the last year with any rust, at least that would go for 90's and above...

Now Chevy's that's a whole other story...

 

In the midwest I have seen hardly any post 1997 F-150s with rust in visible spots from the road, but I have a friend who's family has a 1995 F-150, and like nearly all F-150s in that range, I have seen rust above the black wheels on the bed, but even though I have not researched this, I think it is a very common problem.