Where are your first signs of Body Rust?

Obviously not many old/high mile 3rd gens out there but I do know of a few. And there are lots of fleet 3rd gens that you may see on the roads occasionally (Orkin around me). Many car models in the past are especially prone to developing body rust in specific areas.
For example:
Chevy Silverado's have rear wheel wells rust out
Subaru's typically first rust out in the rear quarter panels
My second gen Started to rust out at the bottom of the tailgate.
Floor pans/cab corners on classics
I'm sure you're all familiar with others..

Being in the rust belt, I don't that these are specific to a few cases and are typically more wide spread problems due to various reasons (manufacturing defects, pockets where water sits, frequent rock chips etc..).

If I would have known before the rust started on my 2nd Gen and my old Impreza (typically because these are hard-to-see areas) I could have probably prolonged or even prevented the rust to start.

For example on the 3rd gen, the lower front door ice buildup problem, I could see this being a future culprit.

I'm not talking about frame rust, that is obviously a exhausted topic..

anyone starting showing signs of problem areas that could be addressed before its too late?

 

Idk, about the tacoma, but it was about 6 years when my emergency brake in my tundra no longer was able to pull up. I looked underneath to find the cable brackets, and the brackets that pivot on the brake backing plates all rusted up. I had been fluid filming the chassis, but those points seemed to be a problem compared to the lighter surface rust elsewhere throughout the chassis.