sentences:  During its production, the exterior of the Phantom saw little change; an exception was the modernization of its destination sign (switching from a rollsign to an LED display).Dual or quad headlights were offered (with the latter becoming the most common on transit buses).While a mandatory design feature on the Phantom School Bus, a rear window was a rare option for transit/suburban Phantoms; Monterey-Salinas Transit and King County Metro are the only two transit authorities known to have ordered Phantoms with a rear window.