A tachometer from Ford Orion (diesel) was used in this project to Fiat Uno with fuel engine 900 on single-point injection. In diesels, signal for tachometer is taken from alternator, there is not counting system. Such tachometer was mounted into clocks of Uno. Then a pulse cable connected it to the engine compartment. You have to find paths with +12V power in those clocks and solder the outputs of the tachometer to them. Is there is no pin of a signal for the tachometer, you probably have to break the circuit which is not used and connect to it. In a place with the motor temperature, where an indicator is supposed to be, you can find a tachometer dial. After turning on the system, the number of rotations should be calibrated with a potentiometer, which was placed on the PCB of tachometer and a stroboscope.