Weight comparison between a Hemi Dart and a Hemi Barracuda.

View attachment 1715817154 The bodies had no modifications other than big block/convertible bracing. Back seats were removed and that is it.

Well let us narrow this down even more to the rear torque box only, that you found on the Formula S BB 4-speed cars, and most, if not all of the SB manual trans cars.
Have yet not seen any picture of any of the SS hemiĀ“s having the front reinforcement box, that the convertibles had.