I remember reading the hayden cooler use for the ATR aux ic is a comercial oil cooler unit, so you can't order them through any hayden dealer, they have to be able to order commercial products..
Just in case you guy´s don't find the Hayden coolers.
This is my setup. Got two of Perma Cool competion 301 from Summit in my truck, kind of where the stock in mounted. Johnsson pump...works great. Made a scoop to get higher air flow thru the heat exchanger.