Hi again. I had a closer look at the photos available in the topic and I'm going to make some guesses and suggestions.
First of all the wagon was painted green as it is actually a passenger wagon (luggage)
Secondly they look like during the years have been heavily modified.
Δτ 1514 still had one
side door, while the other one has been replaced by planks. The existence of the "rain-drains" reveal that a door was once present there


I also think that the
end doors are later additions to ease access to the passenger wagons.
The
roof "box" and the
ladder don't seem to be standard additions as we can see at the following photo.

It would be nice if we had a photo from the 50's or 60's.
Till then I suggest that if one would like to model a ΣΕΚ wagon (as I do) should build it just painting the wagon straight out of the box
Of course, If one prefers to model an ΟΣΕ one should go for the modifications.
what do you think?