The M-10002 at Cheyenne, Wyoming. The train's regular second power car is missing; a power car from the M-10003 through M-10007 series is in its place. Note how it is higher and of a different profile.
It had two power cars, the lead, cab-equipped one fitted with a 1,200 hp (890 kW) V16 Winton 201-A diesel engine and the second equipped with a 900 hp (670 kW) V12 Winton 201-A that had been removed from the M-10001 when it was rebuilt. The two power cars were articulated together with a span bolster, giving them an effective wheel arrangement of B-B+B-B, but they were not articulated with the train and therefore formed the Union Pacific's first separable diesel locomotive.
The train was of nine passenger cars plus the two power cars, making it at eleven cars the longest streamliner trainset yet introduced.
After the introduction of the new EMC E2 locomotives for the City of Los Angeles in December 1937, the train was reassigned to the City of Portland to replace the M-10001. In July 1941, the trainset was placed in storage after it was replaced on that route also. It was reactivated in April 1942 to operate a Portland-Seattle connection. It was withdrawn for the second and final time in May 1943, when the passenger cars were removed. The power cars were eventually sold to Northrup-Hendy for gas turbine train testing in December 1946; they went for scrap in 1947.