The ornamental design for a connectingsleeve for extensionladder, as shown and described.
FIG. 1 is a perspective view of a connecting sleeve for extension ladder showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a perspective view thereof in a state of use.
The dashed broken lines in the drawings illustrate portions of the article and form no part of the claimed design. The dashed broken lines showing of the extension ladder in FIG. 8 illustrate the environmental structure of the claimed design and form no part of the claimed design.