The Amel "C" drive design presents a novel marine engine mount configuration, namely, there is absolutely no thrust component and the mounts are not fastened to the engine!
Conventional "factory spec" mounts for marine (propulsion) engines are designed to handle three components; vibration dampening, torsional resistance and mostly, a huge thrust resistance. Without the requirement for withstanding a thrust component, I would posit that "factory supplied" mounts are over specified for an Amel ("C" drive).
In fact, the "Amel way" (on "C" drive boats) does not even attach any "engine mounts" to the engine! Instead the the engine is "hard bolted" to the frame carrying both the engine and "C" drive and the entire frame is connected to the hull with "engine mounts" (the "C" drive has it's own "engine mounts" to the frame). These "engine mounts" might more appropriately be called "vibration dampeners".
So, for example, Yanmar "factory spec" "engine mounts" are designed for four independent attachment points to the engine stringers to resist the full HP thrust of the propeller and handle torsion and vibration. On the Amel "C" drive, there are six "engine mounts" - four attachment points that are not independent with respect to the engine and two more for the "C" drive. Clearly a different engineering situation.
Just food for thought.
Cheers, Craig - SN68 Sangaris, Tropic Isle Harbor, FL