Naïla has a 2712 marinised by Gustavson. Seen from the rear the anode holder is at the foremost position, on starboard.
Included pictures are :
– anode holder with some remains of zinc anode
– brand new spare anode holder with brand new zinc
– picture of the entire motor with operational temperatures, the anode holder is where the green arrow labelled “Arrivée EdM 30°C” points (front and right of the engine)
– a spare holder without zinc
I bought new zinc through Perkins distributors (Secodi in La Rochelle). Their description on the bill was “bougie BUKH 2 L=40 D=12 BK002” where L=40 is obviously the length in mm, and D=12 is the diamteter
The Nauticat association can provide zinc holder to continental standards. It may help you.