Bill - The main problem with answering your question is that GM temperature gauges are designed on a non-linear system. If you look at an analog GM temperature gauge, you notice that most of them are marked 100-200-260. It's not a simple question of "X ohms per degree". You should be able to find resistance values for benchmark temeratures (0, 70, and 212 being the most common), but I don't think anyone has published a chart or graph of the temperature to resistance relationship.