Hi Ruskin. S&W used to offer sight blades for replacement in standard sizes. Black or white outline. They probably still do, haven't looked in a while. S&W, Brownells and others should have them.
It comes with a new elevation screw and nut as the old ones get hammered taking it out. You could also buy a rear sight assy, cost more but no drilling and refitting. HTH, 30cal.