It doesn't really matter WHAT version of gmax you have, it's the gamepack/converter that you have installed.
Basically, gmax, BY ITSELF, does nothing.
The latest version of gmax is version 1.2. If that's what you have, great. If not, you can find gmax 1.2 in your FS2004 disc 1, in teh "EXTRAS" folder. Note that the program, tutorials and help files are all separate installs.
Then, you will need the Microsoft GMAX GAMEPACK, available from the Microsoft site - see the sticky post above for links, etc.
You still have to register gmax through
Turbosquid.com Follow the instructions, etc.