One of the 5 remaining Southern Pacific Units leads UP Train ZSIG4 07 Sibley Missouri River Bridge on the BNSF Marceline Sub. With only a few of these SP AC4400CW's left, it's hard to pass up one leading on a stack train. SP Engines leading stack trains was once a daily occurrence here on the Ex-ATSF thanks to trackage rights, but those days were numbered then, and are now over.