Primary electric freight power for the Pennsylvania Railroad was the P-5 class, in the 4-6-4 (or 2-C-2 axle) arrangement. Earlier units in the series were boxcabs. No. 4780, built by the railroad's shops at Altoona, Pennsylvania in 1934, was the first of the of the P-5a (modified) group, built with a center cab affording better protection for enginemen in the event of a collision. It is shown here in an illustration from Modern Power for Today's Trains. By mid-1965, all P-5s had been withdrawn from service.