Hello Aero1946,
i am absolutely no expert in tool boxes but the first 43 dated aluminum toolbox has the absolutely typical serbian green colour inside. It looks a bit like RAL6011 Reseda Green and i have not yet seen other eastern block armies which use this particular colour. Can you have a close look if this colour was also on the outside of the box? The serbs also had russian letters on their military stuff and usually used the darker green on their wooden military boxes for exemple. But sometimes they painted items in this dark geen colour with a brush. I have not yet seen this dark green painted with spray guns.
Till to the 90ies the serbian army still had a little bit of original german ww2 stuff in their arsenals, so from time to time you find german WaA (Waffenabnahmeamt) stampings on this green military stuff. I am no expert with german ww2 markings but all in all from the stamings and from the serbian green colour i would say that this could be a german ww2 toolbox captured by the yugoslavians from the german army in ww2 and it was still in use by the serbian army till the yugoslavian war ended in the 90ies. After the war a lot of their military stuff was sold and since then this stuff appeared also in germany via austrian gun dealers.
As i said a small percentage is original german ww2. After ww2 the serbs reproduced some of these items in large quantities for their army and spray painted them in this light green colour. Often you find serbian army "BK" markings on them.
There are people which buy a small lot of this serbian made post war stuff, put german waa markings on them and sell them as original german ww2 for pretty high prices.
Be aware of "original german ww2" toolkits sold on ebay, allmost all of them are serbian post war stuff with fake german ww2 stampings. It always puts a big smile on my face when i see that it was sold for extraordinary high prices and even well known collector experts say that these are real german ww2 made. Absolute ********.
You often recognize it on the painted letters on wooden boxes, its pretty difficult to age the colour so if you see painted letters which look too good on old wooden toolboxes etc. be careful.
