I tried to photograph it on the rear quarters, but its not easy to do. Took 10 pics & just can't see it in the pics.
I made a video & that kinda works because when I move the cameras you can see the light & images bend as they pass through that lower area.
Easy to see with my eyes, but hard to photograph.
basically its a few inches above the lower bottom edge & parallel to that edge of the rear quarter.