I have only one thermistor, 500 ohm, installed, in the lower of the two fuel levels.
I could not find a 600 ohm thermistor readily.
The 500 ohm functions, i.e. it turns on the light controller, but prematurely. Once the fuel warms up the low fuel light illuminates, regardless of level.
I have not installed yet a 100 ohm resistor, as am unsure of it's compatibility with fuel.
I don't have any pictures, got the thermistor from Mouser, and rely on my intermittent odometer for fuel level.
Tank is dry at max 190 miles, or less, according to speeds.