I just saw this on e-bay:
That is a case belonging to the DW-3000 from the 1980's. I have seen pictures on the DW-3000 before but did not think much of it untill now when I see the pictures of the inside of the case.
That thing looks like it can take some serious beating, it is rated to 300 meters. It seems built like a tank . Perhaps the DW-5XXX was not the thoughest of the bunch back then . This one seems to be able to handle even more abuse then most G-Shocks!
Here is a picture of the watch itself:
Strange that this watch is pretty much unknown!