I can't help but I think that the epoch classification that Marklin gives in the catalog is slightly "off". There are cars that I recall seeing in real life in epoch IV that are classed as epoch V in the catalog.
Is there a website about real trains where I could find that information? Like dated photo's of real german goods cars/trains. I'm specially thinking about the huckepack cars (like 82271) and the large schiebewand cars (like 82411) or the FS refrigerator cars. Of all these cars I saw complete trains of them in the 80's. And there are others like the 8655... Some variations clearly are epoch V, the DB AG logo or red colour gives this away. But of a lot of others I doubt.
Certainly the 82411 type of Volkwagen, there passed a whole train of them at least once a week through the station. And of the FS Interfrigo cars there were whole trains in the goods sidings.