The Pennsylvania Railroad operated 425 Pacific type locomotives of class K-4s, all but 75 of which it constructed in its Juniata Shops at Altoona, Pennsylvania. Like most of the railroad's steam locomotives they were numbered randomly with only a few large blocks of sequential numbers; thus their numbering ranged from 8 to 8378. Carl Weber provided this view of K-4 No. 518 an ananymous photographer snapped at Bay Head, New Jersey in the 1950s. After World War II the PRR upgraded many of the K-4s; Mr. Weber comments, "She has the full 'modernization' package of mechanical lubricator, stoker, and front end, with the solid pilot, smaller headlight in reverse position with the turbo-generator, and the 'maintenance/inspection veranda' mounted on the lower third of the smokebox front." No. 518 was one of 111 engines that rolled off the Juniata erecting floor in 1918.