is there a 1" hole in cab floor above accelerator pedal? (or plugged hole?). That was for the starter pedal and one of the spotters that would confirm it is indeed a pre-64 truck that had a R6602 gas engine.. If so, you most-likely have an IHC, but it could also be a Mack or Diamond-T , which were built in much-smaller quantity.. IHC had the lions share from 1951 to 1963. I ran into several IHC 5-tons during my service and owned 4 at one time , but have only seen one gas Diamond-T and two gas Mack's advertised during the last 25 years , for what it's worth .. We can't always rely on a Title year , ie: we have per tag and other features, a 1953 IHC M62 .. However the SF97 person ignorantly titled it as a 1980's AMGeneral.. Imagine the nightmare that one is going to be to get registered. GSA has been totally unresponsive on the issue for over a decade now
IHC used a 4-digit numerical VIN on the 5-tons .. What would be interesting to learn from members who may have a Diamond-T or Mack build, is to compare the structure of their VIN. If different from the IHC format, it would certainly hit your nail on the head
.. On another computer I have several pics of VIN plates from deuces and 5-tons that were at the first online auctions of long ago, showing build dates, different builders, and VIN structure of the rare trucks including Mack and Diamond-T.. That computer has a bad MB and in permanent storage at this time. I probably have a backup disk, also in storage, unfortunately