I had high temperatures on my transmission too, 195°F to 215°F, but I was able to get rid of these and push them down to 150°F to 185°F. the hottest reading i get is under heavy acceleration uphill on a very hot summer day: 200°F. Here's my setup:
- Temp-Sensor in the outline from the transmission to the radiator.
- steel-line sections for the connections to transmission and radiator
- Delafield hoses to link up the transmission to the cooler
- deep trans-pan with cooling fins
- Heavy duty 3-row radiator for the engine (gives better cooling for the transmission too)
- got rid of the stock fan and put on two large electric SPAL-fans used in BMW M3's, triggered by a temp-sensor in the cylinder head.
Since then, i got no more issues with heat. the only "down" is the sound the fans make. they howl like jet engines, once they reach full rev-speed. but that's only for a short time, as they move huge amounts of air through the radiator. when the engine hits 210°F and is not moving in traffic they cool it down to 185°F in 9 seconds.