I can vouch for the Cold Case 3" radiator, though it took two tries to get it right (I hope). The first lasted about 9 months before failing at the left side seams shortly before our Big Bend/Ft. Davis/NM/Palo Duro Canyon trip in January. Aluma-seal went into it and I traveled with 3 gallons of 50/50 and ten gallons of tap water; used maybe half a gallon of pre-mix so I can also vouch for Aluma-seal in this instance. Called Cold Case before leaving, sent photos of the leak, got a new radiator shipped back for only the shipping and it was there when we got back.
Interestingly, it fits a lot better than the first one - no bracket mods needed and seems to cool better, even with the Tru-cool in front of it. Did a great job pulling our trailer through the mountains of Tennessee, Virginia, West Virginia, and on into Ohio and Kentucky last month in the 100+ degree heat.
