The ornamental design for a surfaceconfiguration of a gearshift, as shown and described.
FIG. 1 is a right, rear perspective view of a surface configuration of a gearshift according to my novel design, the left, rear perspective view being mirror symmetrical;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view thereof; and,
FIG. 6 is a top view thereof.
The broken lines are for illustrative purposes only and form no part of the claimed design.