I'm not sure (because the models dont tell us AFAIK), how to tell the date of a particular type of model without resorting to applications that could be costly.
My best suggestion is to perhaps download blender
www.blender.org
it's a free open source 3d model generator, quite capable of making anything you want and exporting in .3ds. I believe it's possible to import the Zax model and then save and export from Blender. It's been a while since I did it and eventually found blender to be a more powerful (if less easy to use, but hey, its free) model generator. You can always find tutorials on youtube and at cgtalk.com to help you learn new software.
Maybe someone here could help you as well. I do not have the ability currently, but the community is full of helpful people.
Best of luck! Keep us posted!
#XPression