Re: SVRy turntable

Was the mainline bridge, 12A, in the same location as where the turntable now crosses the Powder River, or was the turntable moved a second time to its present location? If so when? Also, does anyone know the origin of the turntable? The builder's plaque from the Passaic Rolling Mill Co. Paterson, NJ has a date of 1880 I think, although the last number could possibly be a 9. In either case, it must have been built for another railroad and then sold to SVRy in 1890 or later. One possibility would have been the Utah and Northern which was just crossing into Montana to Dillon in 1880. Does anyone have valuation reports for either railroad that might clear this up?