The ornamental design for a six-shooter vehicle gear-shift knob, as shown and described.
FIG. 1 is a right side elevational view of a six-shooter vehicle gear-shift knob showing our new design. The knob is shown attached to a vehicle gear-shift lever which is shown in broken lines for illustrative purposes only and forms no part of the claimed design.
FIG. 2 is a right side elevational view thereof, the left side being a mirror image thereof;
FIG. 3 is a top plan view thereof; the bottom plan view being a mirror image thereof;