Surprisingly one of my suppliers have a replacement of these in stock, but they are in a pack of 25 and they don't do any smaller quantities. From there specifications, Hole spacing 30.8mm Hole dia 6.3 Length 73mm Width 50.8mm
the ones i had i tried redrilling them to suit the bar and it wasnt having it well hard the lot of itSerrated sections likely are hardened, but plain sections will mostly be sharpenable. I still have a knife sharpening table for 4’6” mower knives that my Dad used to sharpen back in the 1950s. Sections available at any good agricultural outlet.
if it drills its soft ish if it wont its hard plainly putHardness ranges from ‘glass hard’ (brittle) to fully annealed (as soft as it can be) with several recognised ranges in between. Look up hardness testing and you will find files, of different hardness, for assessing the hardness of an item being tested.
no need to go in to the terchnicality of it


