As far as I know the z31's are where they figured out how to keep the cars from not rusting through the fender wells and body. I am not sure however about the 280zx's, but I have seen some serious rust on any of the older body styles 83 and older. I live in SLC, Ut. where there is plenty of salt on the roads for about 6-7 months and my 86 never had any rust through 10 years of daily driving.