The Classic Pack updated to version 2.4.1
The Ore Converter is a craftable block that will let you convert ores between mods. This is required for Galacticraft Extra's, as Phobos lead ore gives IC2 lead ingots.
Type in the modpack name (The Classic Pack) or paste the following url into the search box.
Finally, click Install at the bottom right of the launcher after you select The Classic Pack from the list on the left. The launcher will handle everything else!