Way back, my friend and I used to run our cars. He had bought all his cars before we had first gotten together. Then one day we both bought the same car - a Wild Ones Ford GT. After we bought that car, he left his pit kit at my house and said he'd pick it up the next time we got together for racing. Well, it's been about 35+ years, and he hasn't come back to get it yet. He now lives halfway across the country and only comes home for one holiday a year. And every year I ask him when he's going to pick it up.
Anyway, the point is that his Ford GT has a closed rivet chassis while mine has an open rivet chassis. I don't think either of us ever swapped them around, so I believe they came that way.
I think that's possible. I do have at least one AFX closed rivet chassis too.
Joe