Although we don't have any problems with rust here in Texas, it seems like there are very few IDIs here compared to other places I've been and most the old trucks around here have just been beat, its getting tougher to find these trucks anymore...
I have noticed this trend as well, most of these IDI's are up North and that salt is brutal!
I have a 97 K1500 that spent most of it's life in Illinois and Indiana. Only has 87000 original miles but the rust took it's toll fast! Had to replace gas tank, fuel pump, all brake and fuel lines...
The farmers/ranchers down here are crazy rough on these trucks! I really paid attention since getting my own. And if it's a bullnose or bricknose, it's a gasser. It's the early powerstrokes on up that are really popular. What's ridiculous about those is what people are asking for them and what they are really worth, given their condition.