Just a word of caution, more for those who are not too familiar with German railways and not wishing to offend anyone.
Simply put our area of interest here is Deutsche Reichsbahn (DR) 'Epoche II' (1919-1945) or Deutsche
Reichsbahn-Gesellschaft (DRG) http://web.hs-merseburg.de/~nosske/EpocheII/e2x_d.html
. Post war became 'Epoche III', then IV etc. but the railways of East Germany before unification were still DR, hence the caution.
Wartime German stock was still used by both East (DR) and West Germany (DB) of course well into 'Epoche III' (1949-1970). It's actually much more complicated and is a hobby in itself.....http://web.hs-merseburg.de/~nosske/EpocheII/
(use the Google translate button)
Hope this helps