S6.3 Equipment combinations. Two or more lamps, reflective devices, or items of associated equipment may be combined if the requirements for each lamp, reflective device, and item of associated equipment are met with the following exceptions:
S6.3.1 No high-mounted stop lamp is permitted to be combined with any other lamp or reflective device, other than with a cargo lamp.
S6.3.2 No high-mounted stop lamp is permitted to be optically combined with any cargo lamp.
S6.3.3 No clearance lamp is permitted to be optically combined with any taillamp.