I have been struggling with getting a stable reading on my MGL Odyssey for the Rotor Tach. Without going into all the gory details I have gone through at least 4 tach senders with no luck. Finally I came up a solution. If anyone is interested I can supply a part #. This thing is rock solid and CHEAP. Including the cable with preinstalled connect I think it was about $30. I am currently using only one steel mass but plan to add another in order to balance out the induced vibration.