Hey guys, my first post here. I have no idea where im supposed to post this question. I hope this is the right place. I have a 1973 Plymouth duster with a 360la motor from some other unknown vehicle. The temp gauge is not working. It stays on cold and does not move. I have taken a jumper wire from the purple sending wire at the sensor and grounded it and the gauge jumped to all the way hot so I know the gauge is working. I replaced the sending unit or sensor twice but still does not do anything with engine running even though the engine gets warmed up. I tested voltage at the wire where it connects to sending unit and the voltage jumps around or fluctuates between a couple volts on up which I’m assuming is normal but not sure exactly. Can anyone give me an idea on what I’m missing here?