Kulvers, I think we are talking about a different thing.
The part I am talking about is on the top left of the piece in the photo I linked to; it is a triangular shaped protrusion to the side.
It ought therefore to be present on the top right of the piece in the second photograph as the angle is reversed, if indeed it is the same piece.
I cannot see it. (I don't think this is the same piece of the plane)