Chihili Q (#119) had a Forman system installed which was cheaper and subtley different to avoid patent infringment. My stern gearbox had rotted and was quite wobbly but I don’t recall seeing any fill or drain plugs on it. I replaced the old system with Hydrive hydraulics this year, since a bespoke new gearbox would have cost £5000. If it would help I can post pictures of my gearbox before I sent it away to Mark Jenkins of PARSONS MATHWAY MARINE, 129 PRIVETT ROAD, GOSPORT, HAMPSHIRE, PO12 3SP, 0845 3664126 or 0788 6510164; he was very helpful and could readily distinguish a Mathway from a cheap copy!
Adrian.