Garth, The additional cooler will help the trans more than it will your overheating problem. I would be looking at other causes for that problem. But if you're already set to install the additional cooler, you should mount it where it will receive maximum air flow. Since you have A/C, mount the cooler in front of the condenser in sight of the grill. Also keep in mind it's an additional cooler, and should be used in series with the cooler in the radiator.