[sick472]

I would bet that the I6 radiator is less effective than a stock v8 radiator (less cores if not smaller dimensions). That, right there, is enough to warrant a new radiator. Unless you plan to put the truck through some heavy trailer pulling or racing, you don't need an external tranny cooler. I personally don't think a cooler can hurt, but it needs to be in conjunction with a radiator, not alone.