You need only ONE installation of GMax v1.2...
You can add any or all of the SDK's export tools in separate folders within GMax, in a ..\gamepacks folder. As you can clearly see from the screenshot below, I have SDK gamepacks installed for FS2002, FS2004, FS2004 Scenery, and FSX.
As you add the SDK export tools to the ..\GMax\gamepacks folder, there will be a desktop icon file in each of the SDK tool folders, which you should then right-click and "Send To the Desktop." To start GMax, choose the Desktop icon for the version of the FS you wish to use, so the correct gmax.ini and plugin.ini files will be used to pre-configure GMax automatically. ;)
