The guy with the Nimmo Machine black 57 Bird said the dual fours option wasn't available in 55, only 56. Is that correct? He also described some modifications to the Black bird. The engine is set back about 3 inches. The rocker arms are lightened and the springs that keep them in place on the rocker shafts have been replaced with metal tubing with shoulders on the ends as spacers that slide on the rocker shafts.

57 Black Tbird 312/auto

Also not only were the dual fours not offered in 55, but they were only offered in 56 as a over the counter dealer option, and at that they were not sold to the general public, only to registered race car owners, because of limited supply. The 56 2x4 set up is very different than the 57.

  JUST A MIDNIGHT CRUISE DOWN THUNDER ROAD!!! TOM DRUMMOND MIDWEST DIRECTOR 57 FORD INTERNATIONAL