The "version number" issue has been discussed so many times on the forum, and it doesn't make any sense to have it, since there's a "Check for updates" feature.
You might have installed GSX starting from a certain full installer with its own version number, but since the GSX *CODE* (as explained on the manual when minor updates are discussed ) can update its code to the latest version, and it DOWNLOADS it anyway, the version number you installed with doesn't make any sense anymore, since you already got the most current CODE when you ran the installer, and you get the Live Update notifications too. So, what's your version number now ?
You can't say, because you might have the latest code but, as also explained on the manual, vehicles and liveries are NOT updated with Live Updates, they have their own separate Vehicle update installers.
That's why it doesn't make any sense to say "which GSX version you have", because you might have the latest code, but not have the latest vehicles.
If you are not seeing any Live Update notification, this means you HAVE the most current CODE.
If you download and install the current vehicle update installer, you can be sure you also have the latest vehicles and liveries.