From the same manufacturer as the gauge. For most outboard gauges you need a sender that has 33-240 ohms of resistance (hot to cold). The gauge and sender must match.
I discovered that in fact this is not the right place, it's a water pressure port! I now have a Smartcraft Tacho that reads the engine temperature accurately.
I discovered that in fact this is not the right place, it's a water pressure port! I now have a Smartcraft Tacho that reads the engine temperature accurately.