The ornamental design for a lightbar for the rear of a truck, as shown and described.
FIG. 1 is a front elevational view of a light bar for the rear of a truck
showing my new design;
FIG. 2 is a rear elevational view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a side elevational view thereof;
FIG. 5 is a front elevational view of a second embodiment of my new design,
the second embodiment differing from the first only in the number of
lights.