I've seen them before at Delk's near Ashboro. Was told it was an Air Force addition, for what purpose not sure - other than a top, as the shape is a bit odd. Seen them on Expo and lots of comments about making the trailer look like a coffin! I've thought about trying to pick one up as a starting point for a top, but too much $$$ for me at the time, and I've got less $$$ now...