I completed a study of this stamp as a test of what I need to for all the others. This is one of the simpler stamps in that it had a limited run (all of 1936) and was printed on one paper (my 1E1, the cream medium thickness paper).
This stamp was issued January 1, 1936, and here is a cover from January 4.
This is the first paper (1E1):
There are two catalogued plate varieties in Klass/Kneitschel:
long vertical line across argentina section of map
retouched left numeral background
there is an additional plate variety I find, and it seems to be in one of the master dies because I find two variations:
the most common has a broken curl midway along the right side edge,
here is a detail
the second variation also has a line break that I find in two separate specimens (one on cover).
here is the detail
for those who can read Spanish, I also have scans of the three major catalogs for the regular issues and the officials in Kneitschel (the most authoritative source, it seems):
Officials in Kneitschel