for Ga-4: Györ
http://www.me109.info/display.php?a=e&fid=6552
http://www.messerschmitt-bf109.de/di...lle.php?id=203
But, curiously, no Ga-10 .. just G-10, Györ made, see WNr production batches.
Ga-2: IAR Brasov
http://mmpbooks.biz/mmp/books.php?book_id=115
All IAR made wore three digit codes on fin/rudder, no WNr.
No Ga-6.
Both being producted and assembled OUTSIDE not exported.
For E-3a:
see
http://www.preservedaxisaircraft.com/ where they are effectively named Ea-3. What about original identification plates on preserved machines? Any photo available?