the grill is from a
57 big truck - the hood is 57 as well - and considering the 56 and 57 hood emblems are the same, and that hood bird was a 57 option, I wouldn't be suprised if you actually have a 57
if it has the original ID tag on the drivers door post, that could tell if someone just customized it or did a little creative title swap ... although it could be a 57 first bought and titled late in 56
Bill