stupid question how do you get these stainless wiper arms off?

On my 64 Valiant the Metal part of the blade is riveted to the arm. As far as I know you either change the complete arm/blade assy or just a rubber "refill".
There used to be a "kit" that would allow you to use the 65 or later arms on the 64 earlier pivots. But I don't know if they are still available. Maybe @slantsixdan knows