I don't have any information on the Bx38 but have some experience with the Bx-37. I have two of the Bx-37 cars. One is anIntermountain car that features the small herald. The second is a Sunshine car that I bought completed at a Santa Fe meet.
The Sunshine car had the large herald and this was so noted on the box. I had a number of photos of the Bx-37 none of which had the large herald. I wanted to validate thus and contacted several Santa Fe experts and posted the question on the STMFC list. Nobody had heard of this.
Several years later I was looking for something else and came across a Richard Hendrickson article on war emergency boxcars in Mainline Modeler and lo and behold there was a photo of the car. No information was given save for pointing out the large herald. I came to think that this was a "one of" created on a repaint where they did not have