The original temp sender on my 55 GMC with 503 motor is not functioning and replacements are 'unobtainium'. The thread size is 7/8 NPT. I can easily obtain a universal sender with 1/2 NPT and could use a face bushing/reducer. However, it seems that 7/8 to 1/2 NPT reducers are also generally unobtainium. The original GMC part # is 1513385, a web search for which leads to 0 results. There are a lot of NOS senders on Ebay of the same type, and one or more of them might fit, but being of different manufacturers, and application/measurements not known, that is also somewhat of a dead-end. I don't need to know the exact operating temp of the motor - just need a relative indication. Your thoughts/ideas?
