Head Gasket Leaking at 55K miles ?? Bone Stock, no heavy pulling, normal driving

[HBarlow]

Like others above, I have never heard of a low mileage Cummins engine with a leaking head gasket. Cummins head gaskets don't normally fail on an unmolested engine with that few miles. And also like Bob suggested, there is a good chance that truck had a magic black box installed during its prior history.