blades for a Champion 5 foot finishing mower?

I need a set of blades for a 5 foot finishing mower I pull behind a 45 HP tractor. Does anybody know where I can find these? It carrys 3 blades approximately 20 1/2 inches each. I have tried the local tractor places and the local Agri Supply store in my area. The only thing I can find on the mower deck is the words:
Champion 5 foot.