The ornamental design for the speaker box for automobile, as shown and described.
FIG. 1 is a perspective view of a speaker box for automobile showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a right side view thereof; and,
FIG. 7 is a left side view thereof.
The broken line showing of the speaker box for automobile is included for the purpose of illustrating portions of the speaker box for automobile and forms no part of the claimed design.