1940 and 41 regular trucks used the same housing as the interior lights of a 40 car, as did the cabover trucks thru 47 did. screw tabs have been added to the truck lights to better secure the lenses, the truck lenses are glass and quite heavy as compared to the original plastic lenses of the car interior lights. 40 interior light lenses were of soy bean plastic and very thin-actually had a classier shape than the glass lenses