We always called them "Disconnect Boxes". They certainly have their advantages, and we used them exclusively on all of our span wire-mounted signals. However they were a significant source of trouble calls, which is why many localities don't use them.
I think they're generic junction boxes as well. Did a scan of Carrier and Gable and some hardware manufacturers we use (Pelco, etc) and couldn't find anything.
-Nick B. Shelby Twp. MI, The Northern Fringe of the Metro-Detroit Region
Thanks to all who replied. I just went with a square waterproof box for home depot (grey type) My Saginaw cluster is getting a new home in my workshop in Canton.