You are correct about it being a polished strip. The confusing thing to me were the screws in the middle and at both ends making it appear to be screwed on.
There is no airbrushing on either of those photos. Photos that had been airbrushed are clearly marked on the Pholman log as COPY. Here you can see what the whole picture looked like. Those guys are mechanics in the factory Service School and that is their class photo. The date on that photo is 1/22/54.