The underneath is really solid no holes in the box, the cab floor under the seats no holes also, the front section of floor is wood from the factory.
The frame has already been blasted and primered, no holes there either.
The door bottoms are the only patched. The only thing that look like it needs attention underneath is the usual body mount and they are not rusted out either. The gas tank, I never looked at.
Unfortunately all the work that has been done to the body, will require re-doing, note the spray bomb primer, it is also on the frame.