There was something of a traffic jam when IHB 4010 was sitting at Sohl Avenue in Hammond, Indiana on January 31, 2021 as NS 9841 passes with a Union Pacific EMD in the background. This unit was rebuilt, and lost its signature flat back to look like any other GP40 built for freight service, the only one of the 3 to be substantially modified.

Three Brothers From San Francisco Leave Home. With the end of diesel service on CalTrain, and much digital ink having been spilled over the F40 and MPI36 units now out of work, it is a good time to look back to the previous generation of purpose built locomotives for this service. The three GP40P-2 locos were ordered by Southern Pacific from EMD to serve the San Francisco line after CNJ’s 13 GP40Ps were well received. Largely similar, though with a bit longer frame, they also had a flat back to accommodate a steam generator for passenger service. After the arrival of modern power in San Fran, one would make its way to Indiana while the other two were retained by Union Pacific for freight service. Just short of 50 years later, all three are still in daily service.

https://www.riverrailphoto.com/ihb/e2b67f637
IHB 4010 (née-SP 3197, 11/1974)
Sohl Avenue, Hammond, Indiana