I don't know if this helps Ed, but I ordered my cars after the fact when TTOS was closing them out. I received two 52451 with brown doors. I never paid attention to the Lionel stock numbers before this thread. They may have had excess stock of the banquet cars and replaced the doors to sell as convention cars in an effort to maintain the desirability of the Banquet car?
My car as received:
Sister car after modification. The frame has since been repainted.
Pete