Because these cars have no weight, I had to install sheets of lead eventually become the new floor. To accommodate this, I had to cut the top of the centre beam out of each car with a razor saw.
If the centre beam is a spine, then the short pieces that outline the bottom doors are ribs. These ribs also need to be cut away from the body. I tried hard to keep them in one piece, but some inevitably broke.
Once they were all cut out, I went through each body with a sanding stick to smooth out the interior where the parts were cut away. This was also a good time to go through each floor and body to cut, file, and sand the flash from these two parts in every kit.