Guys - Well, I may have answered my own question!  There is a great builders photo of KCS #18746 on the Fallen Flags website!  The paint scheme is very plain on the car, so I would suspect that cars in the earlier (KCS #18150-18549) series would also have been painted without any heralds or such!

Does anyone have a photo of a car from the KCS #18150-18549 series? 

I want to "backdate" an "O" scale brass model of a PS-1 imported by PSC in 1988.  My cutoff date is March of 1948, so I would prefer a photo of the earlier number series (blt 12/1947).  Fortunately, the PSC model has the early roof on it, but unfortunately has the 6 rectangles on each end.  Fixing that will require a bit of sheet metal work...

Thanks again!!

A.T. Kott