I still am not able to easily separate these two papers.
Most of the large format stamps are 2C, and the paper is clearly bright white. However, some high values, and a few of the low values, are clearly 2D (best example is the 5c Servicio Oficial, which was only issued as an official on this paper).
The straight rays grid is found vertical and horizontal, and that means we have two cylinders used for this watermark. Of course, the 1E4 looks like a straight rays, but I am here only referring to the 2C and 2D papers.
The major stumbling block we have is that generally all of these stamps are rare. If we were able to find specimens postmarked before 1948, they would have to be 2D. I have not come across any large format stamps dated during the 2C era, yet have many of the 20c Large Format Cattle that are clearly 2D, and have a candidate block of four of the 1 peso for this paper.