Sd.Kfz. 305 was the German designation for this Opel Blitz Funkwagen. The Germans named this and Opel Blitz Einheitzkoffer which means is had an closed standardized superstructure. The Truck with the same superstructure could be used for more than one role.
This Opel Blitz, Opel Lighting, was used by a 4 man crew as field radio broadcast unit to send and receive information and orders. The Rack on top is part of the antenna.