I can't tell you what it is. But a few manufacturers used that servo configuration. The PM to BarracudaHockey suggested what I was already thinking. Miniature Aircraft, Hirobo and maybe the Kyosho helis used that type of servo layout. I also remember a Robbe helicopter using the same "rocking" action used on servo design. The tail rotor being on the left side of the heli, with a clockwise rotating head should give the more knowledgeable people some pointers too. All the current designs with a clockwise head, have the tails on the right side.

Sorry I could not be of much help.

Rafael