The blue car i pictured front frame passenger side wasthe first to rust. Had to replace the front torq box and later the frame rail on that side from front box to rear. main cause was the battery leaking acid over time. These days i often mix water and some baking soda remove battery and pour and or spray it around the battery location and into the frame.
Just did it to a Zephyr Z7 i am doing some restoration on. Neutralized a lot of acid.[/QUOT]
The box era and aero era cars ,I believe, had poor placement of the a/c drain and drained pretty into the frame rail causing that right side area to rot from inside out