Nope, not made. Donor cars are your best best. I cut mine out, worked them over on the bench, and welded them back in. You might find a local sheetmetal fabricator to make replicate pieces.
If the holes aren't huge, you might consider cutting out the rot spots, treating the metal, then using the POR-15 floor repair kit, which uses a type of coating on top of fiberglass mesh. The result is a rock hard repair that conforms to the contours of the whatever you are patching. Once undercoated, the repair would be "invisible". Since that area doesn't get stepped on or anything, seems like a reasonable way to approach things. The best method would probably be to find a donor car and weld in whole new sections.
