Coupler Pin - he-ruide
The recommended way to secure the Fleetwood Evolution 3 coupler to the ball is to use a snap pin as seen above.  The typical coupler lock will not work (See the next photograph).

The recommended way to secure the Fleetwood Evolution 3 coupler to the ball is to use a snap pin as seen above. The typical coupler lock will not work (See the next photograph).

Hitchpin