Steve
On my 170 DC. My stress cracks are on the transom where the inset plate that the motor is bolted to, curves outward or backward to the rear two steps with rubber matt. From the bolt holes go left or right to the first curve in the hull. That inside curve.
I also have a few where the counsoles meet the sides or gunnels. They are very hard to see and are in the gelcoat only. These are typical and no problem. The ones that are open and you can see into the laminate(meaning fibers are exposed) are the ones that get you worried.
My old DC is like a rock, except a rock sinks and my boat floats.
fatrap