Der Einheitskasten (The standard box)

Here an original standard box, fitted on top of my Kettenkrad #2:

Here some more pictures showing details of the box::

I need your help! I have some questions about this Einheitskasten:

• What was this Einheitskasten used for?

• What did it contain?

• What fits the brackets on top of the box?

May be you have some original footage or pictures from WW2, showing this type of standard box? Every bit helps!

Email: anfrage@kettenkrad.de