Try our re-instated info resource - "Aladdin's Cave" (Main menu)- sorry it's taken so long to fix
It's the oil gallery end plug Ted. It fits in the alternator end with the 'pip' being held in place by the alternator casting. Make sure you renew the O-ring👍.
And dont try starting the engine without the generatorcasing on or you will e trying to find that plug along with using bags of kitty litter