I think there is a corrosion line or mark on the plate that is throwing you guys off into thinking it's a 3.
I still say 5. A pic of the back should put this to rest.
Charles, you are correct, after a closer inspection, I see the scratch that let us think that's a 3 and not the real 5.
It's much stronger than the downward line in the 5 so that confuses us. Agree with you, its a 5 as it has to be.
Let's try this modified pic..
Josep