Re the general Lee body, iirc, Aurora chassis were slightly longer than Tyco and a bit narrower. I'm pretty sure I remember a Dukes of Hazzard set by Aurora back in their flex track days.

As for the crates, my hunch is you found some one offs. There's plenty of computer programs available to print out, not only crates but entire buildings. Evandesigns.com comes to mind. But these are simple enough someone could have made them with any graphics programs.