Orion97

Thank you for the useful program... though the lmgtfy link was a bit pointless and without reason.

I have an old world which I played buildcraft2 and ic2 on. Now that there are so many more mods that I want to play with, I have a modded minecraft instance in MultiMC with different id's than the ones I used back then. What can I do to change the id's in the world file or does forge have something like this that's automatic? I know that if you uninstall a mod it also destroys the items and blocks, but I want the items to stay, but converted to new ID's. Any ideas? (Not sure if right subforum, please move it if necessary )