78mitsu said:
The best place to monitor transmission temp is the cooler line going to the transmission, it is the hottest oil in the transmission. just go to the hardware store and get a t and you may need a flaring tool and the proper bevel flare for Stainless (if that's the kind of tubing) ...
Actually thats not the best place to monitor it. Transmission fluid can handle the high temperatures going through the transmission for a few seconds. But when its exposed to temperatures above 200 degrees for extended periods of time is when it starts to break down, and then your tranny takes a dump. So monitoring the fluid directly in the pan is the best place.
Mag Hytec, Hughes and other aftermarket tranny pan vendors put a temperature sender port in the high capacity pans for this very reason.
The transmission on my Superudty has a 1/8 npt diagnostic port on it that we put the sender in, but my gauge is Electric. Since your mechanical, it looks like you will have to weld a bung into your pan.