This bike is very similar to 2a and 2b. The rims, handlebars, black sprockets and vertical foot pegs seem to be a match. The big difference is the German Engray-Maico minibike engine. Possibly this engine was swapped into the 2a frame.
The clutch cover looks too small to have a fluid drive mounted on the engine. Maybe this bike had a fluid drive mounted on the transmission. The Engray-Maico puts out 16 HP. The other side of the Engray-Maico engine looks nothing like the 2a and 2b pictures.