XJ6 S1 fuel gauge impedance

Was wondering if anyone knows what the full to empty resistance range is for the fuel gauge in my 1970 S1 XJ6. It has never really worked right and it is time to replace with a new after market one to get some more reliable readings.
Thanks.

Why not get an used gauge? They are not that bad. I don’t know the values but you can always fine tune with an resistor.