Rusty sills are a known problem on the 406 even though they have a galvanized body.
It's the drain holes getting blocked (one at each end of the sills) holding the water inside and rotting from within.
SWMBO's last 406 had this even though I unblocked the holes once a year.
Once you can see bubbles in the paint it's too late, and until then you have no idea.
But you've still got a belting mota for that price.
