I doubt that anything in the chassis is different for an SB car over an FE. The factory doesn't know ahead of time what engine will be put in to it. That is all determined at the dealer level, so the car is the same except for color choices and what other options may be available.
Actually, yes we and the factory do.
There IS a chassis difference for the FE. While I do not recall all the items right now, it IS more than headers and mounts. The rear hoop/cradle has differences and well as several other items. I am waiting for the factory to compare bill of materials for borth configurations.