Here in the Pacific Northwest, there have been many occasions where Amtrak has had to substitute other locomotives on the Cascades (Talgo Train) runs for various reasons when the F59’s weren’t available. Typically Amtrak has preferred to use a P42 but there have been many well documented occasions where a BNSF locomotive would pull the train by itself. In these instances they have used GP50’s or GP38-s’s and GP39’s. So I wouldn’t be surprised to see something of that type, or as mentioned previously a GP60 variant. The GP60/GP60M’s seem to hang out mostly in California and other areas in former Santa Fe territory and have been uncommon in the Northwest, which seems to see mostly former BN geeps.