[1] Forty-six cars in the series were constructed with components salvaged from Presidents' Conference Committee (PCC) streetcars which the Chicago Transit Authority (CTA) no longer needed.

In 1964 they were modified with a locally designed “pan trolley” for the overhead wires on the high speed Skokie Swift shuttle.

Later, cars 23–26 and 29–30 would also have pan trolleys, and 29–30 were also retrofitted with 28 in (711 mm) solid wheels for increased speed.

[2] The Skokie equipped cars, with their pan trolleys, were too high to operate anywhere else on the system.

The Evanston equipped cars, with their smaller trolley poles, operated into the loop.

Fortunately, a handful of 1–50 cars survive today in a number of museums in the United States, aswell as one in Canada.