I am waiting for someone to stick their head up out of the 2 stroke smoke and research demand for a bolt in replacement for the 503/582 engines. IF Rotax runs out of spares, there will be an aftermarket supply? China has a habit of doing this. 2 years ago I was looking for Toyota 12R parts, and found I could buy a complete drop in crate copy motor from China. Now the Toyota 12R would have not been a high demand motor, I would have thought. Last sold in about 1983?