I would say it's an early '55 model that was sold (and thus registered) in late '54. They are just like car models - the new models came out in the middle of the year, not January 1st following a calendar year.
We have the opposite problem with our '56 Safari - it's clearly a '56 because they didn't make the Safari model floor plan in '57 but our original registration states it is a '57. Our VIN number is late in the pack (we're O-6424 of O-6300 thru 6443
)...so it was sold & registered in '57 even though it is a '56 model.
I agreed, record keeping was not a high priority back in the day...