U.P. turntables big enough to accommodate Big Boys were located at Cheyenne, Green River, Ogden, and Los Angeles, although Big Boys apparently never traveled to the far west.
Turntables on the Eastern Division were long enough to accommodate "little" Challengers and Nines -- why these were equipped with such dinky tenders -- but not the later Challengers. When the larger Challengers ventured east, they would have to be turned by the "jack-'em-up" method previously described, which was possible because of the centipede design of their trailing wheels.
For photos of the Ogden table, see Emil Albrecht's Union Pacific Small Steam Power, which despite the name includes many photos of 4-8-4s and 2-10-2s. Some are depicted riding the table.