A quick add-on to my previous post … For the middle car, the interior is somewhat symmetrical, but the exterior body and coupling are different on each side. It is therefore important to know which side goes where.
I found this picture that shows exactly what I need:
While looking for the pictures above, I came across a great video on Instagram:
Besides the correct orientation of the intermediary car, it shows that the interior light is more on the "yellow" color.