Abstract: A crop header includes a cutter bar carrying rotary cutter disks spaced along a gear case. A support beam extends behind the gear case and carries rock guards side by side along the cutter bar and each extending from the beam forwardly underneath the gear case in front of the gear case. Each rock guard includes a rear bolt fastening to the beam and a second forward bolt fastening arrangement to the beam with and is cantilevered forwardly from the supports for support of the forward end of the gear case. The guards include butting side edges each to the next at positions between the disks so that the curved front edges of the rock guards meet at a recessed front position of the front edges between the disks with a cast notch guard member bridging the front edges of two rock guards.