Generally all trucks from GM and Ford will go 12 years with no major rust issues. They all can and will exhibit some surface rust issues but no rust through.
The GM frames can get some surface coat rust issues is the coating is damaged but they will not rust through and if they do generally the truck is so old and used up it is not on the road anyways.
The only real rust though frame issue was Toyota a couple years back and most of them are now gone.
I have never had an issue on rust on a GM truck in any less than 12 years and I live in the snow belt.
Ford also has had more issues on their engines but it is not a major problem either.
