For me I have an 8TB HDD I keep my back up files on and my playable files are on an SSD steam library. To make sure you never mess up, always change the name of the 'Grand Theft Auto V' folder first, before the Modded or Vanilla one that is, and always keep a back up of your modded GTA folder, as wells as your Vanilla GTA folder somewhere. At this point you can just rename which ever game you want (Vanilla or Modded) to 'Grand Theft Auto V' and play it. One will be called 'Grand Theft Auto V VANILLA' and one called 'Grand Theft Auto V MODDED'. After you do this you will have two folders in your steamapps/common folder.

When you want to change back to your modded GTA Game start by changin the name of your Vanilla gta folder ('Grand Theft Auto V') to 'Grand Theft Auto V VANILLA'. That is what we will call Vanilla GTA or 'Grand Theft Auto V VANILLA'. Then redownload GTA and play it online with out mods. rather, if you have mods already, just rename your GTA folder (located in steamapps/common, called 'Grand Theft Auto V') to 'Grand Theft Auto V MODDED'.

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