A head support arm of a disk drive device of the present invention comprises: an arm member having a rear portion with a pivot center and a front portion, a suspension load beam member having a rear portion fixed to the front portion of the arm member and a front portion supporting a head/slider assembly, and a flexure attached to the suspension load member, and is characterized in that the suspension load beam member has a first datum feature, a second datum feature and a third datum feature, the first datum feature is located in a hinged portion that applies a load force to the head/slider assembly, the first datum feature is located in proximity and adjacent to a dimple for providing a gimbal motion of the head/slider assembly, the first datum feature has a V shaped portion, the second datum feature is a slot and is in proximity and adjacent to a spacer mounted at the pivot center of the arm member, and the third datum feature is a slot and is in proximity and adjacent to a front end of the arm member.