We recommend to install a Polyflex Flexible-Coupling between gearbox and levidrive.

Polyflex Drive Saver
It reduces vibration and acts as a predetermined breaking point in case of a sudden and possibly hazardous stop of the propeller. It helps to protect both, gearbox and propeller in case of an accidental stop.
Check out their site at:
www.polyflex.com.au
About Rudi
Mr Scholz gained his academic qualifications in Germany and holds an MBA (Diplom Wirtschaftsingenieur, U of Braunschweig, 1988), postgraduate qualifications in industrial engineering (REFA Ing, Institute for Industrial Engineering in Hannover, 1988), postgraduate certificate in welding engineering (SLV Welding Institute, 1985), master’s degree in shipbuilding, naval architecture and marine engineering (Diplom Schiffbauingenieur, U of Hannover, 1983), and a certificate for building wooden and fiberglass boats (Opelit in Frankfurt, 1972). He has also studied in the Department of Naval Architecture & Marine Engineering of the University of Michigan in the USA.