The two on the left differ in the form of the link between the actual footrest and the bush; the casting marks are hardly visible.
The third from the left looks like a rough casting (India? ), but that can be due to heavy pitting (got it when already grit-blasted); it has a faint casting mark.
The one on the right has a clear casting mark 66-4913 but looks like it has suffered an accident. All have clear, sharp splines.
Which ones should I mount on my bike?

email (option): viaconsu # planet dot nl

Just take the pick of the litter! Personally, I like the idea of having a casting number on mine.

email (option): britool51@hotmail.com

The second one from the left is the nearest to the correct shape with a nice regular curve between the mounting and the footrest part..The 'criss cross' forging is frequently worn away on the upper surface..you can get over this by removing the footrests, turning them upside down and refitting them on opposite sides, thus exposing the unworn 'underside'.....Ian

email (option): ian@wright52.plus.com

Arent the Indian ones cast iron? These cast iron ones would will crack and shatter if hit. I thought the original ones are steel that bends if hit. Is this true?

The bad ones are cast iron; don't know if good Indian-made, cast steel ones like the original exist

email (option): viaconsu # planet dot nl

put in vice and hit with hammer if steel it goes clang, if cast iron you get a nice bit of scrap metal.

My M20 came with footrests with the letters M.R.C stamped in centre of crosshatch pattern. Now im thinking these might be Indian..

email (option): fuzzyempire@hotmail.com