just wondering if im being stupid or reading it wrong but are the roofs interchangable? any help is super appreciated

I’m printing the rails and they are coming out great. However, the connections for them are extremely loose. Is it supposed to be that way? Seems like it will be problematic on the table. I’m using a Bambu xc1.

Anyone running into the issue with the sides on the flat bed car not fitting right? If I want to use the sides I printed, I’m going to have to drill them out.