Sorry I took a while to respond- I was out of town and wanted pics for you.
The rust was extensive. The radiator was sitting on the frame and because only one person drove or rode in it before me, the rockers dropped rust every time the doors were opened.
The radiator support was taken from an earlier model expedition at a junk yard. We drilled out the welds my frame, removed what wasn't rusted away and bolted it in the cleaned up and slightly fabricated junk yard piece using the drilled out welds. We then covered it in primer and underbody coating. It's difficult to get a good picture with it in.
We went the opposite direction with the rockers. Aftermarket generic sheet metal rockers that were long enough to cover the entire length were used after the rusted areas were cut out. With the doors closed everything looks good. Opened you can see where we primered and coated (but not too bad) and then underneath there was hardly anything left to weld to, but it looks pretty clean. The "We" was mostly my father welding so I couldn't help you on the type. I know it was spot to spot with a torch. Then we ground it down smooth, primered and coated.
Hopefully that helps.