Seaboard92
Engineer
I believe that at NYP, the platforms for tracks 9&10, 11&12, and 13&14 can handle 18 cars. The trains that long were pulled by two GG-1's or one E60 between New York and Washington. No cars were added enroute to the Silver's. The seasonal Florida Special was a shorter train, and it added a dome sleeper at Richmond.
I believe they have since done some track work at NYP since then which has caused the issues. You can still see the relics of the old days in Newark and Philadelphia where the platforms are much longer than any of the current consists. That's basically a 1,530 ft train without the power on it. That is a lot of train.