Transmition cooler on your trannies, not really needed. Unless listed above doing some heavy mods.
Now on the GM V6 performance trim trannies, they can use aftermarket coolers as the factory radators arent really up to the task of cooling GP GTP, G6 GTP (2006 3900s) , even the GA GTs with mods can use coolers as there also possible eairly tranny failer from heat.
If you do go with a tranny coolers heres the diffrence the general diffrence on temps
The tube and fin coolers do very littly by way of cooling. In testing average diffrence was anywhere from like 4-10 degrees.
The bar and plate coolers faired better they ususally cooled from 12+ degrees under harsher conditions.