Michel is referring to the Series A 500cc oil-tank and toolbox top lug spacers. (Page 41 ASL). I don't have physical access to the lengths at the moment, but I can tell you from an excellent Glenn Shriver sketch that they are 1.5 inches long for the toolbox and 1.25 inches long for the oil-tank. All bolted-up through the frame by a 5/16 dia stud, 4-7/8 inches long, with CEI threads at each end about 0.5 inches long.
Peter B