Hi Boden
Well, this part of the instructions really looks like I was expecting modelers to guess what was hiding in my head. Additionally, the markings (although correct) can also be confusing.
The brackets needed to glue the grating and side rails can be made in two ways. Either as in figure 46, by gluing together "empty" profiles from the appropriate 103 parts, or by gluing together the appropriate 104 parts glued to 1 mm cardboard, and then giving the edges the right bevels by cutting off the white areas with a knife and a file. In the case of part 104, at the end, you should glue the brackets with appropriate 104 strips to mask the cut and sanded edges.
And this is probably where the biggest embarrassment appears, because unfortunately parts 103 and the interchangeable parts 104 have no logical numbering. Parts 103e, g, i, k, l are interchangeable with parts 104a-b, 104c-d, 104e-f, 104g-h, 104i-j respectively. You use the remaining parts 103 (all P/L and horizontal beams 103f,h,j) regardless of the version chosen.
In other words, instead of complicated and difficult parts 103 (which resemble 4-legged spiders) you can glue them from parts 104 in the form of thick layers of cardboard, make appropriate chamfers and mask the edges with stripes (or paint). In my model I used parts 103, but many modelers suggested to make a simpler version from thick cardboard. (I am personally not sure if such a version is simpler, but I agreed with the modelers' expectations)
I've searched the photo gallery and unfortunately I don't have any others, but maybe this construction render will help.
Greetings
Tomek