Amtrak's SDP-40-F locomotives garnered a reputation for derailments that soured some railroads on using them. Oddly enough, while BN and IC were imposing speed restriction on the big SDP's, the Santa Fe and SCL were running them @ 90 MPH with no problems. The knee - jerk reaction to Amtrak's weight saving specifications that resulted in a hollow bolster HT-C truck were refuted by tests that showed the actual cause of the derailments was the lightly - loaded baggage car behind the power. The roadbed characteristics of certain railroads was also called into question. ( It is worth noting that Santa Fe regularly ran the Southwest Limited with three SDP's; SFe would also trade CF-7's & SSB-1200's for used Amtrak SDP's and run them in freight service. )
As well, Amtrak lost interest in the SDP-40-F as they converted their passenger car fleet from steam heat to Head End Power. While the SDP's were built with HEP in mind, with the twin steam generators mounted in skids for easy change - over to HEP units, the as - built HEP run - through cables were found to be too small to handle the voltage requirements. The F-40-PH was a better answer.