Queries regarding Leopard 2A5 on Exercise

The Tankograd book on the Leopard 2A5 (ref. 5075) includes photographs of the vehicle on exercise.
Fitted on the turret front is the DARKAS gunfire simulation system. Does anyone know the length and outer diameter of the individual tubes?
Also, certain examples show a rectangular plate (to the rear of the loader’s hatch), on which is mounted an array of electronic devices. What exactly is the purpose of this, and are there any close-up photos that would enable me to scratch-build the feature?

Thanks,

Paul

Likely to be AGDUS duell simulator, available here from PSM