A Model 1 or 1/S with the addition of an engine mounting plate becomes a Model 3 or 3/S. It is available in standard SAE flywheel sizes as well as made-to-order sizes. The standard cylindrical hub is available in a variety of ANSI (SAE), DIN, JIS, and agricultural spline bores for hydraulic pumps and other applications. Various standard flexible element materials are available for specific torsional, misalignment and environmental requirements.