Question regarding slogans found on ATSF Bx-69 class boxcars
Awhile back, I picked up a Branchline kit of ATSF 17189 (Bx-69 class) that has the slogan "The Route of the Super Chief". While looking for photos of the Bx-69 class (ATSF 17000-17499) online so that I could renumber the car to match a photo, I noticed that cars within the series carried different slogans to include "The Route of the El Capitan" and "The Route of the Chief".
Car with the "El Capitán" slogan
Cars with "The Chief" Slogan
My question to the Santa Fe experts...Was there a method in Santa Fe's madness as to how the slogans were applied to cars within a given series?
Modeling the BN/MILW in North Central Montana, Great Falls to Shelby, Circa: 1979