I need someone that knows a 400 trans. I want to install a trans temp gage and don't want to put it in the pan. I would like to get a faster reading of temps going up or down. There is a plug on the drivers side that is a test port. Can this be used for my probe? Is it hot fluid or cold fluid (like from a return cooler line) that flows past it? If this port isn't able to be used, then I'll just place the probe in the hot out line going to the coolers. This 1/8 npt hole just looked perfect. Any help will be appreciated.