After helping in the other thread [hopefully helping] I figure I'll ask for something I am missing

I am after for my older Bombora longboard the round mast base that goes directly into a hole with a tab that stops the round male nose turning so the upper section turns and compresses a rubber o ring which expands and grips the internal female hole thus creating friction to hold it in place, the top of it is a serated circular handhold, which has a rectangular base with a rope tendon which connects into a bullet shaped mast plug ..

there usually are two mounting holes on board all earlier bomboras that used this, later ones used the fin box mast track system that is standard today,
asking if anyone can supply one, id even buy a complete smaller board if it had one so i can use the longboard with the shortboards parts