Some more pics...
...interesting that, our GEAR oil drain and fill plugs are standard 8mm threads with only a 12 mm head.
I'M TALKING HERE ABOUT MODELS LIKE, GRAND DINK AND YAGER.
So, in case of a loss you can use any, watch lenght, standard M8 bolt with a 13mm head from your hardware store (pls see pic to compare).
MOTOR oil drain plug is a different story.
It's a M12 pitch 1,5 thread with a
17 mm head, so a standard M12 bolt CANNOT be used.