Dan, do you know the material the dice are made from? They are not 1939 Las Vegas Horseshoe. To early and highly unlikely a Nevada casino would have used opaque dice. The only clues you have is the date and possible the material they are made from. Any maker can put whatever date they want on dice and at that point the question would be why date them. The most obvious answer is to make someone think they are older that they are. Sorry I can't be more help, but not much to go on.