Automatic Transmission - Tranny cooler

I am buying a 3500 stall in about two weeks and a tranny cooler. I was wondering where exactly the cooler is going to be installed. Obviously it helps keep the trans cooler but how and what kind should i get? And what is the reason I need one to go with my stall? I am getting one, just wondering.

Nevermind answered by stickeys.

Nevermind answered by stickeys.

right in front of the radiator.. zip tie it so it doesnt move around.. there is a metal bar right in front up there where you can zip it to..