Mine came from factory with a trans temp gauge mounted in the pan. There is some discussion as to the best location. Some will argue the pan is better, because then you know you are keeping up with the cooling. Others argue that an inline gauge is better because it tells you the temp of the trans itself. Personally, I preferred the pan, as your trans temp is not so much of a specific threshold, as much as it is heat over time shortens fluid life. Yes there is a threshold, but you will know if you are getting close. The other reason is that at least in my case, I had an oversized pan. The sensor was near the top, so if the pan got a little low, the gauge would read zero. It gave indication, long before the level was critical.