BC,
Your picture is of the first 67 design. There was a factory part revision in 4 6 67 that changed your 3904186 clip to 3919006 clip that is shown in John's picture and was carried over into 68.
Could you show a picture and dimensions of the screw 9418359 that holds the clip to the throttle lever? It is the same for 67 and 68.
Bob