Well, concerning the light rack on the truck I haven't seen anything that points to that. There may or may not be a flood light built into the back of the truck's roof but that's about it. I will leave it to the truck experts to comment on whether this make/model has that feature.
In response to sherbetjello, I would hope that LE has determined that it was a person in the back of the truck, despite their suggestion that the tuck was hauling equipment. I know that the FBI has all of the same techniques that I used, and if they've done anymore than an hour of work on that photo you can trust that they know it is a person. It doesn't necessarily make that person a perp or a suspect by any means, but for that reason I can understand why LE may have waited this long to release the photos to the public.
And let me just clarify... finding a person in the back of the truck was not my objective when I started this. It was simply the only conclusion that was left to me after looking at it from every threshold and every depth. Nearly every rendering that I looked at (of the ones focusing on a discernible object in the bed) depicts the form of a human body at the very least.
The more detailed renderings show unmistakable features that are simply unique to a human face-- concave eye sockets, brow line, protruding nose, a mouth, flat forehead, cheek bones, the hairline, even the contrast between the hair and the skin. I tried as hard as I could to identify some type of recognizable work equipment in the back of that truck, but no matter how you slice the pixels in that picture, the only object that comes up is a very distinct human body with a noticeable human face. It is undeniable.