FIG. 1 is a perspective view of a support unit for mounting on a vehicle showing our new design, and with the broken line showing for illustrative purposes only and forming no part of the claimed design;

FIG. 2 is a left side elevational view thereof, with the opposite side being a mirror image;

FIG. 3 is a front view;

FIG. 4 is a rear view;

FIG. 5 is a top view;

FIG. 6 is a bottom view; and,

FIG. 7 is a exploded perspective view thereof.