Circa 1918-1922 - Difficult to date these 4 wheel cars as there are very few characteristics that differ over the years. The gravel car did change one thing on the lithograph sometime prior to 1925, the Capacity listed on the side was increased from 100,000 to 150,000, although old bodies were often used on later cars.

Above is the earlier litho with the 100,000 capacity, below is the later version with the 150,000 capacity note the slight difference in color of the litho.

Unusual rubber stamped variation that was used in the middle 1920s.

Circa 1925-1930 with larger capacity lettering.