I just checked with a mirror and flashlight. There is an enormous great 1 cast into the magneto cap next to the plug cable for cylinder number one - duh!
In my defense though it's painted black, it's buried under a cluster of wires, it's up against the firewall, it's dark down there and it's in a different position on the magnetos shipped with the new experimental Lycomings than that shown in the diagrams I have access to - including the one that came with the engine.
Jim