ok i have a spare 3 wire o2 sensor and thinking about addding a o2 a/f ratio sensor to the datsun.
One wire is for the heater element, another for ground and the 3rd is the signal to the ecu.

As the datsun does not have an ecu, do i hook thi sdirectly to the guage or does it need an ecu for the correct sinals?

should work like a multi meter and just process voltage drops and spikes (reading lean to rich roughly) so there fore is a ecu needed at all?

not looking for the untimate in tuning efficiency but to give me an idea of rich/lean to some degree.

at least readings wont be as fluctuating as no ecu mapping to correct the a/f ratios in a carby car, so will be a progressive reading

looking at the jay car kit or possibly a guage.