Yanmar Tach very expensive
I looked into putting the Yanmar tack on my 3QM30 some years ago. I can't recall what it cost, but it seems like it was in the neighborhood of $300+. I ended up buying an electronic tach for about $50. The only difference from the user's standpoint is that if you use most any of the 3 stage regulators it will not begin to read anything until the charging kicks in from the regulator. This is usually from 30 seconds to a minute, depending on the regulator and settings. It picks up the pulses from the regulator as it charges.