In all the flail mower threads I don't remember seeing RR products listed as a parts source so thought I would provide a link. Just ordered a few blades and hangers for the old Ford 907 I am fixing up. Prices are a little (pennies) better than FlailMaster and 2 day shipping is cheap.
https://www.rrproducts.com/repparts.html
https://www.rrproducts.com/repparts.html