The Great Northern caboose in Seattle is assigned to a BNSF local job out of Stacy St. Yard ( aka Seattle International Gateway ) that works the old U.P. / Milwaukee Road leads to Union Station. This includes covered hoppers of flour to Gai's Bakery plant on 6th Ave. South, served from the " back " ( West ) side lead along the 5th Avenue Busway, North of Spokane Street. Also occasional boxcar loads into MacMillan - Piper on 6th Avenue South at Holgate Street. This job also switches Northwest Container and the lumber re-load at 6th. Ave. South & S. Alaska Street, just a bit North of U.P. Argo Yard.
The GN caboose features a rooftop horn for shove moves across the many street crossings in this area.
The U.P. Argo yard has been home to an Espee bay - window caboose for some time. It's used for shove moves on the local along East Marginal Way South.