Southern Pacific Railroad and Denver and Rio Grande Western Railroad participated in the tests, but both found the locomotives unsuitable for service in the rugged Rocky Mountains through which the two railroads ran.
Pacific Railroad și Denver and Rio Grande Western Railroad au participat la teste, dar amândouă au găsit locomotivele nepotrivite pentru a fi servite în Munții Stâncoși accidentați prin care au trecut cele două căi ferate.