634 (A-D)??

Hi all, I'm having trouble deciding which exactly this block is: The previous owner (see My Introduction for details on that) has it identified as 554. However, I've measured many times and find it is 11x10.5 (am I saying that right? it measures 11perfs. at the top and 10.5 down the side). Now I'm seeing the 634 has varieties...including an ear variant.

I'm posting 2 pics, one full and one close-up of the ear. Your thoughts and guidance would be hugely appreciated : )

Although side plate numbers like that are usually a sign of flat plate printings [SC554], on the 2 cent 1926 [and also presidential] there were experimental plates [not scarce however] that had side, not corner, numbers.
This is a SC634.

This was the first "Electric Eye" Plates (as listed by Johl) Electric Eye Plates

Electric Eye - In 1933, starting with the two-cent stamp, the Bureau of Engraving and Printing began experiments to improve the perforation process. The plate block at right is from one of the first electric eye plates ever printed. Note the position of the plate number, it's not in the corner as rotary press plate numbers normally are. The electric eye makes use of a photovoltaic cell employing a beam of light to aid in perforation accuracy. Although the experimental sheets had a series of dashes down the very center of the sheet and a single dash in the center of the left margin, the electric eye markings we are familiar with were not added to the sheet margins until 1939. The philatelist may note that many stamps after 1940 always seem to be well-centered. The electric-eye had a large part in this.
Electric Eye Reference -> http://www.1847usa.com/Glossary/E.htm

Thank you so much for the information : ) There is so much to learn about collecting! This is a straght up 634 then, not one of the variants?....so tell me, is this a good find in the hoard?

I'm still not very adept at what should jump out as great, or just a brief smile and nod ;-)

Also I am confused (please forgive my ignorance) but if this is the electric eye thing, and that started in 1933, then how is it a 1926 issue? Is that when they started with this design? I'm so sorry for not understanding what you all must consider common knowledge : (

From one "Klein" to another ... just a normal SC# 634

Got it, awesome, and Thank you :) I just found a bunch of MNH blocks of SC645....question, there are the initials or letters A.B. on the corner in lots of white space of a block of four....do I still label that a plate block in my database?

Yay for German/Austrian heritage! (though I have none...Irish/Cherokee here).....My husband is the very proud Kleinsasser!

Should be. Better number blocks are the "Star" Plate numbers. Blocks with "printed initials" are also preferred by specialist collectors and will bring a slight premium over standard blocks,

We fell off the truck .. Hungarian on this side of the bus.

Best,
Hal

Great information! Thanks again!