When we were creating the resin kit for the Northern Pacific 39000 series boxcar, we could not confirm the location of the reservoir on any of the cars that were refitted with AB brakes. We had a decent picture that told us where the triple valve was, but no good picture of what would be termed the right side of the car.
So we released the kit with only a K brake option and left it the individual modeler to make his own determination as to the reservoir location and the method of securing same.
So it figures that after many sales and much discussion a photo shows up.
When we were creating the kit, that was the location that I had guessed would be used. But I remain convinced that had I made a definitive statement to that effect a different photo would have surfaced first that proved me wrong.
The joys of the Model Railroad business.