basically, it fixes to a new bulkhead to take the thrust from the prop, that is normally taken by the engine and gearbox and through the engine mounts into the hull. ait also has a constant velocity shaft so that engine alignment to the propshaft is less critical.
So.... I made up a bulkhead in cardboard, and after MUCH trimming and measuring to get it in the right place, and to fit the gap neatly, I transferred the shape to 18mm ply and cut it out with a jig saw... as is expected in these cases, the wood didn't fit neatly, so more trimming until it was a good fit, the propshaft was central in the cutlass bearing and the distance for the engine/gearbox was right... this took several hours!
Finally, I sanded the hull where the wood fitted to ensure a good bond, and mixed up some epoxy and micro balloon filler... I've glued the wood in place roughly using this 'paste' and once its set, will remove the aquadrive that was fitted to ensure alignment, and glass the wood in properly.