Federal commercial vehicle regs:



say that any truck over 80" wide needs two clearance lights (at front corners of roof) and three identification lights (front center of roof 6"-12" apart). I have seen AD series trucks with three lights total, one at each corner and one at the center. I think at one time they used three for the widest trucks and one for "in between?" I have also seen pictures of green lenses used on some of these trucks instead of amber.