My '58 parts book shows 3725688 as the part number for the '56 emblem (6 cylinder version), with the red bowtie on the black background. Could be a misprint.
The emblem pictured, with the red background, was originally unique to the '57 truck, listed under part #3738185. However, at some point between '58 and '68 (the years of parts books that I have), the '56 and '57 emblems were both listed under that number. It seems the '57 emblem replaced the original '56 one.
So, while the emblem shown may not be original to '56, it can still be considered a correct replacement.
