RE: DL-50 engine
Bottom is the one but go back and do what FOOPED said. You need another hole in that composite arm. Then bolt it toshorter carb arm. Otherwise it will rotate on the throttle shaft.
PS: Came back toexplain in more detail. You will actually end up using both arms. You will use the short metal one that came with it and the composite one will be bolted on top of that metal one. They will share the same screw that goes into the throttle shaft (it may need to be a little longer. A 4-40works good in this hole). BUT you will need one more screw and nut (4-40) to go through the outer holein the metal one, and the new middle hole you drilled in the composite one. So you will have two sets of fasteners holding the composite arm onto the metal one. Then the third outer hole in the composite arm is what you will attach your linkage to.