From recent humbling experiences:
You will need to check out a few things before you know what needs doing:
1) poke with a knife or pointed hammer at the opposite (in)side of the box session/chassis leg. If it´s bad, the chassis leg needs to go.
2) poke with a knife at the front end of this box section/chassis leg, just where it meets the bump stop thingy. My bet is that it´s soft there too.
3) Look (from the outside) for the spot welds along the underside of the inner wing. This is where the inner wing is welded to the box section:s low edge. Take a good look at the spot welds from the spring shackle and forward to the bump stop. If they - or rather the material between them - look "swollen" , it´s bad.
Probably it´s time for a new chassis leg. Replacement panels with reasonable fit are available, make sure you get both the box section and the corresponding outside plate.
I think that spring hanger looks patched already, I might be wrong, tho. All the more reason to rip it out.
Edit: Dang, did you see that? Your newbie newcomer (me) is actually giving some advice! That felt good - actually knowing what I ´m talking about for once
cheers/Richard