Well, the TS-3 wasn't the right size from the supplier. 3/8" threads rather than the 1/2" threads. Got another one from him though instead. Have put it beside the other 3 senders I have and let them all get to the same room temperature, then measured their respective resistances. One varies by about 80 ohms less than the TS-6 model. Since these are NTC resistors, as the temp falls, the resistance rises. So, I guess logically, if I install the one with the lower resistance, that would equate to a higher temperature on the gauge and may possibly work for me and my situation. Will try the install this weekend to see and report.