A two-piece grab arm housing for a grapple mechanism useable on a grapple attachment is described. The grab arm housing includes a lower arm housing with grab arms mounted to the lower arm housing, and an upper arm housing mounted to the lower arm housing. The upper arm housing and the lower arm housing are movable relative to one another in an x-direction and are moveable together in a y-direction perpendicular to the x-direction. In addition, the upper arm housing includes an opening through which a main beam of the grapple attachment can extend.