The ornamental design for a rackstructure for a utility vehicle, as shown and described.
FIG. 1 is a front perspective view of a rack structure for a utility vehicle showing the unique design;
FIG. 2 is a front view thereof;
FIG. 3 is a side view thereof; and,
FIG. 4 is a top view thereof.
The rack structure for a utility vehicle is shown with breakaway away lines in FIGS. 1-4 of the drawings to indicate indeterminate length and width. FIGS. 1-4 of the drawings are shown with broken lines to indicate environmental structure or boundaries that form no part of the design.