1965 C10 factory frame supports question??

[Wildman65]

I'm not sure what you call it exactly but it's inside the frame rail on both sides, just in front of the axle. It's just a plate that is factory riveted in there fore extra support. Must have been a week spot. And now a rust troubled spot! Does anyone make these supports or what are my options? I can post a pic later today unless you know what I'm talking about. I really need to remove them and would like to do some prep work in there and put a new set in.