The aluminum tank will be more durable. I've heard rumors the 6.0 I/C has better flow. If you get a used cooler, place it pipes up on the floor, and pour in some aluminum-safe degreaser (like spray nine.) Add water until you see the liquid in the end tanks. Rock the cooler side to side to run the cleaner through the core. Drain and repeat until all the oil residue is washed out, and your cleaner/water mix is relatively clear. Do a couple time with water to rinse out any cleaner residue. stand the tank on end for a couple days to dry out. I had to do this on my SD when the engine started have major blow-by and was being pulled through the intake system.
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