I own a pontoon that is difficult to see the motor from the Helm and needed a guage to help tell me what the motor was trimmed out to. Well I had found this kit (Mercury 820540A3 what I used ) & possibly 820540A1 that will fit and works well. It seems difficult to find but hey are still available. It took alot of research to find the right unit and kit, the Mercury dealer could'nt find anything and had said it was a dealer option at purchase and recommended buying a newer engine with the option. Well I hope this helps someone in the same situation. I added a few pictures of the unit (some are a little blurry).