Just upgrade my Ozark game and what I saw was that the JTS 3.0 version refused(clicking install did not start the installation process) to install when I selected a different folder than my old installation folder. Seems that the game intended to upgrade my existing installation, but as I didn't need the old one anymore I just removed it an afterwards installed 3.0.
I don't think that earlier versions have such installation routines so afaik it would be best to install any pre-3.0 version after 3.0 was installed because he might be unable to install 3.0 separately if an older version is on the installed.
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Lieutenant General Christian Hecht
Commander I Corps, Army of the Potomac
"Where to stop? I don't know. At Hell, I expect."