These diesels were made by Alco and arrived at the PRR in 1947 and in 1950. The book "Pennsylvania Railroad Diesel Locomotive Pictorial Volume Six - EMD and Alco Freight Cab Units" (2001, Withers Publishing, ISBN 1-881411-32-X, pp 449-452) is an excellent reference for these locomotives.

The Life-Like models were released in 2001. They are great runners. The photos below are of the A and B units.