Thanks! Learn something every day! Now that I see that, the memory is coming back. Both those lines should fit into that black socket at 45 degrees on either side. IMO, so when looking straight on to the tach socket, bulb is down, electrical wires are up, longest fiber line is on the pass side, shorter fiber line to the drivers side.
So here is the ashtray fiber optic's I have. I know it's a 69 version since it is still attached to the top plate. I would really like to know how it was mounted on the ash tray side. The fiber optic just has a ribbed rubber tube attached. thx