Heat-sink trans coolers. Who's got them, and how do you like them?

The derale coolers have fins on the inside as well. I've spent a couple hours scouring the net and simply cannot find any BTU ratings. It's kind of odd because from what I can tell, derale is a reputable company. The most common application I've found is guys using then in fiberglass body hotrods and a couple camaros as well as people using them for cooling full hydro steering systems in offroad rigs. None of these people mentioned their results though. :/

My car is a '72 dart custom sedan with a lightly built (higher comp, mild cam, edlebrock intake 4bbl carb) pushing a newly rebuilt a904 with a higher stall converter (around 2300).

I canceled the order for the tube and fin style. Looking at B&M super cooler line now, unless someone has a glowing review of the sort that I posted a picture of.

I'm heading up to the mountains with spotty pretty slow internet so responses from here on might be a bit slow.

Thanks for all the input so far guys! :)