Firewood posted:
the second generation frames kept the rounded end geometry but changed to the more recognizable fixed tab and slot couplers which is easier to see on an open frame car...
though Marx frames are easily swapped, in the case of your car i would not rule out a factory production first generation C&S body on a 2nd gen frame while the transition to the plain black frames was in progress...
things then went a bit crazy with the number of variations the 555 reefer went through, but that's another composite i'm working on...