On Wednesday, February 6, 2019 at 7:43:08 PM UTC-8, Nick Kennedy wrote:
In the Wings and Wheels classified there is a French Registered ASW20C Motorglider

Some pictures show a clean fuselage top and there is a photo with a rather large Konig engine with a folding prop attached on top of the fuselage. Does this whole engine/propeller go into the fuse? The motor and prop look really big in the photo.

Does anyone know any history of this modification?

It's known as the "Top".
Been around for a while. You can remove it and fly as a real glider or put it on and enjoy the noisy smelly thing.
Jim