The ornamental design for a rear endportion of a vehicle, as shown and described.
FIG. 1 is a right, front perspective view of a rear end portion of a vehicle showing my new design;
FIG. 2 is a left, front perspective view thereof;
FIG. 3 is a left, rear perspective view thereof;
FIG. 4 is a right, rear perspective view thereof;
FIG. 5 is a front view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a left side view thereof; and,
FIG. 8 is a top view thereof.
The portions of the vehicle shown throughout the drawing views in a de-emphasized and half-tone form outside the broken lines and the broken lines representing the boundary and configuration of what is claimed as the design are all for environmental and illustrative purposes and form no part of the claimed design.