Thanks! On my model I used a plastic pen to start with, cut it to match the upper curves, and then shaped it so it flattened out towards the back. I didn't take any images of that part while working on this model, but I used the same technique on the previous model. Here are some comparisons when I attached that piece. And yeah, there is supposed to be a straight raised piece over the top for the series version of the model... I just wasn't happy with how my attempts at making it looked, so I left it off. As for what it is... I'm not sure on the smaller model. In the later images it has a hole drilled through it, so I think it was used for hanging the model. Given that, I don't think it is just a cover (like on the 11 foot model). It might be part of the dorsal... but I'm not sure. I'm hoping that when faced with building this in the same materials as the original, the reasons for why things were made certain ways will become clearer. I'm already trying to think through how I might do things and then looking at the images of the original to see if they did things in a similar way. Plus I was going to put together a series of questions for Datin... basically to see how much of the building of that model he recalls from back in 1964 so I can match it as closely as possible.