I am tring to repair a low fuel light (indicator) for my 1969 Cougar. This is a 12V D.C. circuit. A relay with a 45 ohm ballast resistor and a thermister (ntc) located in fuel tank. When resistance drops to 10 ohms light comes on. That is when thermister is out of the liquid. The ballast resistor is in parellel with the coil. I am looking for a manufactors order number for this part as no one at parts supply depots will help without one. Any help please.