We claim the ornamental design for the dolly assembly support on a tow truck, as shown and described in the drawings.
FIG. 1 is a top and side perspective view of one preferred embodiment of the design of the present invention, showing a top rear portion of a tow truck, and two pairs of dollies and corresponding dolly carriage axles supported by the top rear portion of the tow truck;
FIG. 2 is a rear perspective view of the design shown in FIG. 1;
FIG. 3 is a top, rear perspective view of the design shown in FIG. 1; and
FIG. 4 is a left elevation view thereof;
FIG. 5 is a right elevation view thereof; and,
FIG. 6 is a perspective view of the assembled dolly carriage portion from the dolly support for tow truck.