From what I understand, the problem with the frames rusting like they have been, is because the formula for the steel that was used when the frames were made, is a faulty mixture. This is why the steel will actually peel apart in layers, which is not 'normal rusting'. This faulty mixture apparently allows the steel interior to rust. Usually rust will happen on the outside of the steel first & then eat its way through to the inside.
I could be wrong... if someone has a better explanation, please let us know.
Yep, you'd think by now that Toyota would have fixed this problem. However the worrying thing is that this same frame rusting problem was also in the 1990's Toyota Tacoma pickup trucks. And we would all have thought that Toyota would have solved this problem before they released the brand new Tundra line back in 2000. But they did not.