There were many styles of marker lites under the beds, many had a2 inch hole or so that a lite was mounted behind, those were a beehive stlye lens anout 2 inch long that poartly protuded thru the bed but were mounted on a thin canvas strip so there were flexable, then there are the armord type you see in the link that were mounted on the bed rail, but when you had cattle racks and pulled in too close to the loading shute you ripped them off, so many people put a piece of angle iron under the bed to screw these to and then they had some protection
