The reference article that Larry was talking about from Ed Hawkins is online, it was in the November 1990 RMJ and part of the RMJ Freight Car Models box car book #1:
http://www.trainlife.com/magaz...ovember-1990-page-60
Perhaps someday , with 3d modeling software I can take the ROCO/Bev-Bel undec car I have and re-engineer it without the holes and cast on details.