The tach sender on the Tamd 40 engine
is an inductive sender, and it basically counts the teeth on the injection pump
and sends a pulse to the tach every time a tooth passes the tip of the sender. To generate the pulse both leads from the sender need to create a complete circuit, basically one leg out, one leg back.
Whether this can happen with the tach that you have, of course depends on the internal circuitry of the tach, and probably the manufacturer of the tach can tell you whether itís possible, and how to wire it.
Off the top of my head
I think there are 30 pulses per crankshaft revolution generated by the sender on your engine.
If youíre interested, I think I have an original new tach for a 40 series engine, and maybe a complete new panel. Have to check...