Next question which is better a stand alone install or hooking it up to the return line ?.
Depends on your goals for the car.
If it's mostly a street car, run it in series with the radiator tank cooler.
If you drive it in the winter months, run it in series with the radiator tank cooler.
If you seldom drive it long distance, store it in the winter and run it at the track, do a stand alone cooler.
If you run it in series with the radiator, you should see about a 10 degree cooler transmission temperature over the engine temperature.
If you do a stand alone transmission cooler, your engine coolant temperature should be lower due to reduced heat load.
The transmission cooler may or may not require fans depending on the airflow at speed and if you see a lot of stop & go traffic in hot weather.
All of the above based solely upon my personal experiences.