hey guys stripping underseal and decided to investigate some rust further and found a nice whole, is this a cut out and weld in a replacement job or more serious?
Looks like some water got behind the chassis leg (if that is what it is its hard to get perspective from the photo) and started to rust through. As long as the chassis leg is solid and you can remove the rust just cut out that section of floor and replace it. Bend back the chassis leg and reweld it on. If you wish you cna reinforce it. I would use a good weldthrough etch primer especially between the chassis leg and floor. Then paint it with an etch primer followed by a decent paint and then seal it all with seam sealer.