These are the nuts and bolts that mount my OEM fan shroud to the radiator. The nuts are stamped "CIP" with "GR-5" underneath. The bolt heads have crosshair dashes casted at the 9:00, 12:00, and 3:00 positions with some kind of a Y-ish symbol at the 6:00 position. Thread size/pitch is 1/4-20 NC...