As others have said, the '31 rear "sedan type" fender has the clearance dimple stamped into the skirt. It is used on your slantwindow sedan as well as the Tudor, standard phaeton(4 dr.), straightwindow 4 drs., and Vicky(maybe some commercial body types too). The '30 is the same without the dimple and minor differences such as mounting hole shapes. To my knowledge there is only one repro manufacturer of steel ones, I believe in southern Ohio, regardless of who retails them. Again, as stated they are not the greatest and will take rework. You can modify them or '30s for a dimple. If your originals are not too bad, assuming that's what you have, the $600 or so for repros may be better spent on restoring them.