Renault Megane suspension bushes

There is a knocking from the n/s/f of the car and have checked the suspension and i have noticed there is a bush missing. I am looking for a replacement but don't know what to ask for at the motor factors. The best way i can describe it is where the anti roll bar (or what i think is the anti roll bar) joins to the suspension arm. There is a bolt through it and looks as though it's in 3 parts: 1 part under the head of the bolt, 1 between the anti roll bar and suspension arm and 1 between the arm and the nut on the end of the bolt(it might be 1 bush all joined together, i can't tell). The part that is missing is the bush between the arm and the nut the others are worn aswell so will need replacing. I have looked for anti roll bar bushes on the internet but they look nothing like the ones i need.
Can anyone please tell me what bushes i am looking for?