I've personally had better luck with cars. The unibody construction doesn't leave as many places for rust on the underside where as truck frames tend to rust o

I've personally had better luck with cars. The unibody construction doesn't leave as many places for rust on the underside where as truck frames tend to rust out wherever they can't easily be washed, particularly with newer boxed frames. That said, none of my ~25yo vehicles are failing inspection for structural rust, they're all failing because the fenders rust out where the wheel sprays everything.