Am I missing something? I would say the lower cowl is what needs to be replaced, with the upper needing it a little bit. To me, it looks like leaves or something collected in there and just kept it moist and now it has rusted through.
The picture that was attached by topcat shows the upper cowl and in comparing to mine, there are a few holes, but the aprons are attached to where you show and all down the lower cowl as well. They are new parts and the welds are not ground down, so I can see where they were, so getting that off shouldn't be too bad, but it does show that there is a lot of work required to do this... I am just glad they made these parts today.
cb