How can I date a Opus 7?

I just got my Opus 7 back from a tune-up and boy does it sound grand! I took a gamble & bought it used for about $150 and all it needed was few new caps and one new tube. The Magic Eye worked like a champ and no replacement was needed. I even picked up a remote Telefunken speaker for $25 which I will hook up to the Opus, I hope. I don't know much the speaker but it says Hi-Fi Klangbox WB. If it sounds as good as the Opus 7 I will be well pleased. Ok...back to my question...how can I guage the year of this radio. FM goes to 108 so I am thinking this is an export model? Thanks in advance.