2p late issues "dot in blue over UTI of FRUTICULTURA" plate variety

 A somewhat less common plate variety. It is likely only found on a single position in the plate. These three stamps, in order, are 2p1L1, 2p1L5z, and 2p1L6.

I also find a specimen with a variation.

2p late issues "long scratch over fruit" plate varieties

The first two stamps show the same plate variety. It's a long scratch over the watermelon. Both stamps are 2p1L6.

This 2p1L5z has a long scratch from the orange to the pepper.

For this 2p1L6, the long scratch is over the watermelon.

The bottom frame is slightly worn out as well.

2p late issues "dot in blue between CA and AR of REPUBLICA ARGENTINA" plate variety

 This is the most common plate variety I find. It is most likely present in every repeatable block of dies on the plate. I do not know what the size of the master plate is, but usually it is 2 rows by 5 columns for the large format values. This plate variety alone tells us that all of the late issues share the same plate since I find it on the cream frame printing of 1951 (2p1L), the clay printing of 1955 (2pCL2) on the same colors as the 2p1L, the rust brown 2p1L5z Zarate printing of 1956, and the 1957 2p1L6 printing. 

This plate variety also has a line break to the outer frame along the left side of the stamp. There are some ink dots found on some stamps and not others, but these are not repeatable as far as I can tell.

I also find it on the SERVICIO OFICIAL 2p1L5z issue.