Okay, for those who are interested, here are some photo's of an F150 bedside rotted out, due to the use of soft foam sealer, between the inner, and outer panels, during manufacture.
The first photo shows a close up of a piece of the foam, after it was dug out of this whole area.
The second photo, shows a hole, with the foam still visible inside.
This is a 2005. It was built more than 20 years after Toyota proved conclusively, that if you use this foam as a sealer between the inner and outer panels, it will rot out, in certain climates.
I was paid by Toyota to replace both quarter panels on many Camry's, back in the 80's. They they tried this trick, possibly first, and found it caused these issues.
Today, manufacturers still use this product, even though they have to know this can happen.
This is also what causes the quarter panels to rot out, around the gas doors on GM cars.
No amount of rust proofing seems to be able to stop this from happening. And, you can't remove this foam, without cutting it open.
Some may argue, it's a 2005? What do you expect? Well, the only rust through on this vehicle, is both bed sides. And, it's only where the foam is. So, what I expect, is for them to not use a product, that is known to cause the vehicle to rot. But, that seems to be asking too much.
I have also seen this happen on vehicles that were much newer.
This same foam is used to attach the outer door panels to the I beam, inside the door. That is usually about in the middle of the door. Because it's not at the bottom, moisture isn't trapped there, so it does not cause issues.