here in Va they use a mixture of salt and sand but aside from the driveshafts my 98 has no rust on it. the frame has some sort of thick gooy tarish substance on it, unlike any other undercoating i have ever seen on a vihicle, the underside of the truck is not undercoated but appears to have some sort of a clear plasticish film on it, its starting to peal in a couple quarter size places. if its surface rust on a new non undercoated frame i would just have em hit it with a wire wheel then undercoat it, once its undercoated rust cant sustain itself without oxygen.