I think the frame stamping wasn't done at every plant until '56, but if you have the stamped frame number and it matches the vin on the door tag, you have the original cab - the gas pedal mount is what was used 55-57, changed in 58 when the firewall stamping changed slightly .... for the data plate, I'd discount that having any meaning, the one on my 58 doesn't match any of
the 3 Carter shows, it only has 2 very narrow small data boxes, likely different plants had different suppliers various years
for the firwall difference, I'd have to examine my 58 closer compared to a buddies 56 I have stored here, but I know the main difference is a variation in the hood hinge mount bolt holes, so it'd be hard to detect there, otherwise the cabs were identical from 55.2-59 .... and you have a well-optioned truck -
see list here, the options you have were available from 55 on
Bill
