I tried to reply to your latest post on the E setups, but couldn't do it.  Apparently I can start a new thread.  I don't know what is wrong, I'm not a computer guy.

Anyway, the '56 dual four manifold is a different casting than the '57.  I would guess the '57 manifolds were easier to cast and machine, therefore cheaper.  The '57 manifold moved the carb flanges forward a little, I would guess to provide clearance for the larger '57 distributor.  I have a copy of an ad from a manifold/carb restorer that said 102 of the '56 setups were built.  I also have a copy of a letter to dealers, offering left over kits at the dealer's cost of $100!!  I still have my '56 setup that I used to race on my '56 Bird.

John

John - "The Hoosier Hurricane"