Behind the bar OR in the space directly below the radiator would be pretty effective in relation to airflow I'd imagine...
Now obviously you can go "too big" when choosing a transmission cooler with the downside being a lower than specification transmission oil temp during normal operation, how well would a medium sized cooler with an additional thermofan either controlled by a thermal sensor and/or auxiliary dash switch address both temperature requirements?
carvesdodo... where did you fit your auxiliary transmission oil temp sensor & could a thermoswitch be placed there instead OR would a transmission oil line sensor like
THIS one from Derale be better?