Fuel Leak

[Hershel3]

I have a 1993 12 Valve cummins. The truck has started to leak fuel and loose its prime of course. The cause is the round bolt with two flat sides on the fuel pump behind the fuel line. I dont know the name of this pin . I know it has some o rings on it because i changed it and it still leaks but i believe i put the wrong size o rings on it. Does anyone know the exact sizes i need so i can get this baby back on the road.