The OP in that KLOV thread (crazygamer) is who I got these from.
I don't know ArcadeTechGW personally, but I'm certain they've seen EPROMs before. I had someone else say that it looked like there were "holes in them," maybe seeing four of the quartz windows throws people for a loop.
Had some issues with the XP box that runs my programmers, so I haven't had a chance to try dumping these yet.