Wow that is an interesting problem. Here is what I would do to be absolutely sure you are getting what you need:
Email Ludwig directly. Usually there is at least one person at each of the manufacturers that knows the equipment and it's history (I know this for sure at Tama, Yamaha and Sonor) and ask them to be sure. I personally don't know of any Ludwig drum that ever came without the keystone or blue and olive badging but I suppose it is possible.
Here is the Ludwig link:
Welcome to Ludwig Drums - Celebrating 100 Years
Click on Support and then contact us.