Do yourself a favor and run the trans fluid through the biggest double stack (not a tube and fin) cooler that you can fit in front of the condenser in the grille! There are many benefits to this approach:
1. Heat kills the tranny-running the trans fluid through the radiator cooler severely limits the temp the fluid can be reduced to.
2. Trans fluid is VERY hot and will make the radiator work harder cooling the engine on hot days
3. No trans fluid contamination from coolant leaking into the trans from broken trans radiator lines.
4. Cool trans fluid will last MUCH longer than radiator cooled trans fluid. My trans fluid runs about 125-135 degrees on hot days, less in cold weather.
I run dual 18,000 GVW double stack Long coolers in the grille of my GP outside of the radiator now for about 35,000 miles and have had zero issues in very hot or very cold weather. Trans shifts perfect.
Hope that helps!
