That is what I read, but since Toyota and Dana settled the lawsuit, I don't think we really know what it was. It wouldn't surprise me if it was Dana's contention that they applied rustproofing per the specifications from Toyota, but that they settled because it was cheaper than fighting.

Since my Toyota-built frame rusted in the same way as the Taco frames that Dana built in Mexico, I'm skeptical that the fault was solely due to Dana screwing up the rustproofing.

This post implies it was Dana's fault for the Taco frames: http://www.toyota-4runner.org/1942719-post11.html

But then why did my 4Runner frame fail in the same way? As I said, all I've got are questions, not answers.