I have spoken with a 47-55 panel-body-trucks expert who used to provide a lot of good information in this forum. His conclusion is similar to those posted above: the panel-body is most likely the same geometry over all those years. And, most likely the panel-body mounting blocks are the same over those years. And. the panel-body-frame-only brackets for the mounting blocks are in similar locations over those years.
However, a pickup frame would not have the brackets for the panel-body mounting blocks. This might simply require taking the brackets off the panel-body frame and attaching them to the pickup frame. I will try to determine later this evening if there are holes for the brackets already in the pickup frame.
