they all rust, it just depends on what type of rust you can deal with.
d1's at the door sills and cargo door sill. frames get rusty but they have to be really neglected for the rails to rust like 03/04 d2's.
d2's rot at the fresh air intake under the windshield cowl, the seam on the passenger side where the fender meets the firewall, and the frame. like previously stated, the 03/04's frames rot like its their job, thinner steel and the seams at the bottom of the frame collects all the crude inside the rails.
fwiw, i steam cleaned my 03's rails, dried them, then wanted them….the rot just laughed at it. the 99 has surface corrosion but i sand it with an orbital then shoot VHT roll bar paint on it.
i hard waxed it once, but it absorbs mud, salt, etc. and it gets on all my tools when i worked on it. i just switched to VHT roll bar paint. now i just spray bomb a couple times a year.
if you want a nice truck, and plan on treating it like it should be cared for, find a nice one down south and pay a little extra money.