Push And Pull. Crossing Lemon Street on August 21, 2017, UP Y2731 (3GS21B, NRE) was mid-train as it approached the Los Angeles Times Olympic printing plant in Los Angeles, California. Union Pacific Railway’s YJY68 serves multiple customers on track used only by this job, so the arrangement of the train on any given day may reflect operational priorities as on this day it did not reflect photographic priorities. UP once rostered 59 3GS21Bs (Y2701-Y2760), all have been withdrawn from service.