The boy who took the pictures lived in that street, so he is not related to the car.
The license plates are East German ones, but as Carsten wrote, these were "export" tags. Any foreign car allowed in with foreign temoprary/export tags would have to swap the plates for as long as the car was allowed to be driven inside East Germany. When the car left the country, swap license plates again. Probably the car had those old, oval West-German customs/export tags and the owner had to put on the ones visible in the picture to drive through East Germany, perhaps visiting relatives and showing of his new Fury. I don't think the car was owned by an East German, although rumor has it that Western cars trickled through the iron curtain here and there and became the possession of East Germans.
The removal of the side marker refelctors and the changed outer headlights (I didn't notice any of the two details!) lets me assume the car was titled in West Germany before. West German TÜV didn't like side marker (lights) up until the late 1990's or even later. And sealed beams are still not officially allowed.