55.2-59 57 truck

[57tailgater]

To make a '56 look like a '57 I assume you are just talking the hood and grill as those are the basic differences. Hood swap is no issue. To do the grill, you will need '57 front fenders as they have a relief in them for the grill surround where a mounting bolt and flange goes. You also may have to modify the splash pan that goes under the grill and between the fenders to accept the '57 mounting which should be fairly simple.