Truck Repair: n 14 cummins 2000 model, coolant, diesel fuel

Question
recently noticed coolant has diesel fuel smell and oil tint/residue...truck has 1 million on meter.

Answer
you have injector cups that are leaking into the coolant. they will have to remove all the top end pull the injectors and remove the cups that they sit in and replace them with new probably looking at about 20 hours in labor and parts around $1000 at top end.