Anywhere west of Liverpool ranges. Where your van came from nothing rusts, there never seems to be any dew. We pulled dozens of old Holdens out of paddocks out there, they'd been sitting out in the weather for 20+ years, only rust is where windows had been left open and leaves got in making acidic water to rust floors, that or 48/215 to HG utes where leaves got in the rear floor section and caused rust. Your Sandman and Buickzz's were both from around that area, basically rust free. I pulled some HK Monaro doors out of 6" of silt at Coonamble at an old wreckers, not even a hint of rust. My silver HK GTS I sold a few months back has been out in the weather up there for 20 years, rust is the same as it was when I got it. I remember a HQ ute driving around there in all but bare metal, saw it over a 10 year period, metal had dulled after 10 years but barely even surface rust.