As I posted some time ago in another thread, here is my 700R4 transmission cooling problem: First, when you are driving down the road, you probably will not have a cooling problem. In overdrive, the converter is locked up so there is not much heat being generated. Where the cooling problem will show is at slow speeds....putt-putting around the fairgrounds, etc.

I did the following steps with my 350 Chevy/700R4 with no radiator trans lines:
1. First used a flat Derale cooler with a fan mounted horizontally over the rear axle. Blew the air downward. Long pulls in lower gears made trans temp go to 260 deg.
2. Added finned aluminum cooler (long skinny tube with fins) outside of frame rail. Zero change.
3. Added high velocity boat bilge fan blowing down tube cooler. Zero change
4. Moved Derale cooler from under car to above rear tire (this is a 4500 lb jeep). Helped some but long pulls still got hot.
5. Removed bilge fan. No change
6. Changed to Torco synthetic fluid...figured if it was going to get hot, then I should use a fluid that would take the heat. This helped probably 30 degrees on the long pulls. I am at 11 quarts in the system right now.

As soon as I quit the slow pulls (unlocked converter), the temperature falls to under 200.

From what I can tell, you cannot predict the performance of a system by asking other people...it is a personal thing that is related to the air flow on your car...it's not like a radiator cooler....the airflow under the car is so different between cars that it is mostly unpredictable. From what I found, you need to experiment with a transmission temperature gauge installed. I highly recommend the synthetic fluid...costly but apparently effective.

By the way, the trans pan with the little tubes or fins works at speed when there is air going thru the tubes but at slow speeds, there is not enough air mass being presented for it to do much

mike in tucson