Is it behind the timing cover? It sounds like you are saying no. Can't say I've looked and certainly don't want to spread misinformation if this engine is not susceptible to the catastrophic failure some 3.5L engines have when coolant is able to leak into the oil. It would be outstanding if that's not a possible condition on this truck.
It is not behind the timing cover and cannot leak coolant into the engine oil. It is completely external.