My preferred method of automatic transmission temp measurement is an IR temp gun to the fluid pan, can't use it in motion, but easy once stopped.
That said, I really like the factory temp gauge on the 8 speed auto in the Big Horn.
I'll post some pics later.
Edit:
Oh and my other Favorite
OEM Brake controller that works with the ABS shockingly well.
What I used it for Last.
Truck is a Rental $35/ Day unlimited miles.
I've used it to tow A 7.3 Diesel F-250, A horse Trailer, A heavy load of steel, A Celica GTS on a Trailer, A Supra on a Trailer, and probably some other stuff.