Here is the way the sequential production number works.

1953 through 1955 1st Series (Last of the "Advance Design")
TThe code changed significantly in 1953. VINs now had: Series (single letter); Model Year (last two digits of the year); Factory Code (now changed to letters); and Production Order symbols. Each series was separately numbered in sequence for that particular plant (Starting at 001001).

Example -- L54A001901

Series Model Year Factory Code Production Order
L 54 A 0001901

The truck in the example is the 900th 1954 1-Ton truck built at Atlanta.