Transmission Cooler

For a street car plumb it to the radiator then too an external cooler. You need the fluid to warm to a certain temp, it has a functional range, too cold can cause shift flare, too hot and its fail. I can't recall the MFG but there is a valve you can plump in that is thermostatic. It routes fluid to the radiator then when it get hot enough it will open the external cooler circuit too.