I know this is a very weird question that probably nobody has noticed, but if you look closely some 727's have a clear lens at the very far back corner of the top of its tail where a strobe light is mounted. My questions is, why do most 727's NOT have this strobe light while others do. Im assuming it was an option that some carriers wanted while others did not. Next time you guys spot 727's check it out some you will see with tail strobes flashing while others not. During daytime the only way to really tell is by noticing if the clear lens is there or not.