The branches between Ashton, Idaho and to West Yellowstone and Tetonia had been abandoned by the time Eastern Idaho/WATCO took over the xUP branches out of Idaho Falls in late November or early December of 1993. Also the centers of both the Westside and Eastside branches had been abandoned due to the Teton Dam failure and flood in 1976.

I believe the Butte Special was still operated as a tri-weekly train from Salt Lake to Butte up until Amtrak took over when it was dropped. Butte actually served FOUR major railroads - NP's secondary line, the GN branch from the north, the MILW and Union Pacific. Not to mention BA&P, and there were trolleys and another early shortline towards Anaconda. The tracks from Salt Lake through Pocatello, Idaho Falls, Butte and to Garrison were originally the narrow gauge Utah & Northern. UP/OSL bought it and standard gauged it (some of the equipment going to the Sumpter Valley), and at some point the NP got a long lease on the line from Butte to Garrison. UP kept some kind of rights between Silver Bow and Butte which is how their passenger trains got into Butte proper. In its heyday, Butte was roaring and one of the more important cities in the west.

GN only had one RDC #2350 an RDC-3 which replaced a gas/diesel-electric doodlebug on the runs. #2350 was originally assigned to two different trains - one south to Butte, and another north (Shelby or Sweet Grass?). Before the northern run was dropped, this car put on more miles than anyone could imagine for an RDC. WP's use would have come close if WP had been allowed to only buy one RDC-2, but WP was required to run it Stockton to Oakland which required two to be ordered.

#2350 was sold to Amtrak, then to BC Rail. It is now on the Idaho Northern and Pacific.

From memory - so some details may be off.