Does anybody have a resistance reading for a temp sender, say at room temp 20 degrees, that will work with the TR5-6 water gauge. I seem to think that the ones available these days are not quite the right resistance for the gauge, they pick an average for all models it seems. as they seem to read high on the gauge, without actually the temp in the head to be high. At one time there used to be a colour band on the sender to differentiate the different resistances does this still apply, and who