Putting a new sounder in so will have to move the gauges in our volva aqad41 powered boat , is there a cheap easy alternative digital tachometer for diesels that anyone has used ?
actually add temp and oil pressure gauges to that too although they are probably easier to source I imagine.

I remember when the cable or the drive for the mechanical Tachometer died on the old Ford, we put in an electronic one that worked off the Alternator.

We calibrated it by jamming a bit of rubber in the drive on the back of the old mechanical tacho gauge and holding it on the front of the crank pulley. Not very scientific but it all seemed to work ok.