I'm not sure what type of thermistor that is but I found a tutorial called How to: Repair low fuel warning sender online and it may be able to help you, it has a picture of something very similar to your picture.
It seems as if they have replaced theirs with a 1k NTC Thermistor part no. ND03J00102K (in the UK) and USA part no. RL2004-582-97D1 or later part RL2004-582-97K, from Mouser Electonics