Y block Billy (1/10/2011)
I believe the 55 shop manuals have a diagram of the frames. I do know the Vicky and convertible frames have an extra plate welded down the bottom of the frame for stiffness. Almost looks like someone added a patch down the underside of the frame but it is factory.The 55 Crown, convert and Victoria had this plate welded on the underside of the frame for reinforcement. Some of the late 55 models do not have this reinforcement. I don't know when it was discontinued.
Some of the 56 2 dr Victoria's also have this sleigh runner under the frame so it seems that certain plants had frames from different manufacturers. These did not have the heavier outer frame like the rest of the 56 Victorias
56 Crowns, Victoria's and converts have a heavier outer frame (outer half of the box) than the 55 model frames or 56 sedan models. It is 2 ga. heavier. The inner frame of the box is same ga. as the 55's.
marv