That's one of the advantages of having the power car on the TALGO sets instead of depending on locomotive HEP -- any locomotive could sub for the regular power, although at lower speeds due to differences in passenger vs. freight gearing.

It's not the first time freight units have subbed on the Cascades services. In October 2000 I photographed a TALGO set at Portland Union Station with a former SP SD40M-2 (Boise Locomotive rebuild) leading. The maintenance crew at Portland had bad ordered the Cascades cab car with a wheel problem, and UP sent the freight unit over from Albina Yard. The unit pulled the set on #507 to Eugene that evening, then pulled it on the return to Portland as #500 the next morning (the train turned on the Irving wye in Eugene instead of having the freight unit on the rear on the return trip).