If you have had a fuel in the coolant contamination, you will want to check all the rubber hoses. Diesel softens and swells the rubber hoses of the cooling system and will weaken them severely. This will result in burst hoses, usually when you're farthest from help. Or, it might just lead to collapses or a lot of smaller leaks as the hose fails gradually.
At any rate, you will want to check the hoses for swelling and softening as that will happen before they fail completely.
Good luck,
PH