Does the 135c have a different hull than the other models?

Yeah. So basically, they all have similarities, but the difference is at the back, where the 135c has an external cargo pod at the rear. It's not longer or bigger than the other ships, but if you are at the rear and the ship is landed, you can see, obviously, a difference at the back on the bottom because, well, there's cargo there.

Yeah, they are true variants in that they have geometry and hardpoint changes versus modular bits that swap out. You can't take a 135 and take that external cargo out and put a blanking plate in, and now I've got a whatever color scheme it is, blue and orange, I want to say. Blue and chrome.

The cargo is the blue one and the fighter is the darker one.

The gray one. You can't just swap that bit out and change it. They are proper variants.