Pennsylvania Tank Line first appears in the February 1912 ORER with a picture of PTX 1001:

Their entry used a picture of PTX 1061 by December 1912:

In May 1915, the picture changed to PTX 1091. Decent picture here:

The change to the "new" underframe appeared on PTX 3500 in May 1917:

The more familiar cast tank saddles seem to have started circa 1918.

Standard Car Equipment Co. first appears in the January 1916 ORER. The first picture appears in February 1917:

And as a bonus, here are some pre-1917 German/General American tanks:

David Thompson

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