This printing is approximately 10 times less common than the 1E4 printing. The color is slightly crisper.
Here is a detail of the watermark.
The 1E3 was in used in 1943 and 1944.
This 15c 1E4 Small Format Cattle 'Servicio Oficial' shows a scratch to the plate outside the stamp design.
This 1E4 stamp has a small L of 'OFICIAL'
Here are a few postmarked specimens of the 1E4. This printing was in use in 1943 and 44.