An elongated rotary cutterbar assembly includes a housing having a first surface, a second surface, a front portion, and a rear portion. At least one disk is rotatably coupled to the housing, and the assembly further includes a first tab at least partially disposed between the first surface and the second surface, and a tab plane defined by the first tab and extending between the first surface and the second surface. A stop surface is defined in the housing offset from the tab plane towards the first surface, and a disk guard is coupled to the housing at the first tab. A receiver is defined in the disk guard at a location adjacent to the first stop surface. When a force is applied to the disk guard towards the first surface, the first receiver contacts the first stop surface to restrict deflection of the disk guard relative to the housing.