Originally Posted by BigChief

Just as a point of interest, you can restore case hardening of parts like this by simply glowing the part with a torch and quenching in water. Manufacturers use oil hardening steel so they can machine parts in a soft state then they are heated in a furnace and quenched in oil. Glowing with a torch and quenching in water isn't as accurate but still case hardens parts surprisingly well. So if you have an axle or cone that is difficult to replace, it would be possible to resurface it on a lathe with radius stones and lapping polish then re heat treat it to a reasonable case hardness.