Pete,
Is there any other writing or logo on the die? If not, and if the die is 11/16", it is probably #LT0039 in the dice book....from the early to mid 50's, rarity of 4 (10 - 20 pairs known to exist) books for $25 - $50 per pair. Nice friends!

BTW the Reno/Tahoe dice book is from 1999, as with chips, all dice info is subject to change!