From the Pennsylvania Railroad publicity booklet Modern Power for Today's Trains comes this image of GG-1 4929, a 1943 product of the PRR's Altoona shops. After holding the same number for Penn Central, it became Amtrak 923, later 4923 before being scrapped in 1979. The GG-1s, like other PRR electric power, operated at 11,000 volts of alternating current and developed 70,700 pounds of tractive effort.