
It looks like the watch has a Hughes module, this might make it easy to date as the majority of them still have the date sticker in place.
It might be worth popping the back off and having a look, as this will give you the month and year of production - this assumes that the module is original to the watch of course.
A photograph of the Hughes module with sticker can be seen here -
http://img113.imageshack.us/i/compuchronbackje1.jpg/