FIG. 1 is a front left perspective view showing a snowmobile side panel according to our design;

FIG. 2 is a left side elevation view thereof;

FIG. 3 is a right side elevation view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is a front elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

Throughout the Figures, the dashed broken lines represent environmental matter and/or unclaimed portions of the snowmobile side panel and form no part of the claimed design. The dash-dot broken lines represent the boundary between claimed and unclaimed areas and form no part of the claimed designs.