Based on recent work carried out by Rein, there are three 1E papers.
1E3a: Symmetric mesh, rectangular grid, clear porous paper. It has the same configuration as the 1E1, but is a bright white paper.
I find a candidate 5 pesos stamp on the 1E3a, but I am not sure that I am classifying this specimen correctly.
1E3b: cloudy paper with asymmetric or symmetric mesh, rectangular grid