It surprised me too, but I think the rad and the whole cooling system was overkill. They wanted to make sure the 8.1 did not have over heating problem.
I have problems getting my motor up to temp in the winter it gets up to about 160 and no more.
Beside having a 38 inch wide core the fan is supposed to be able to flow 11,000 fpm of air where 4 to 5 is good for any other truck with electric fans..