Gordon,
The Sumpter Valley actually purchased a very large amount of narrow gauge equipment from Utah, entire rosters in some cases. The following newspaper articles give you a bit of an idea...
22 October 1900
"SELLS EQUIPMENT" "Western Narrow Gauge Engines Go to Sumpter Valley" "The Rio Grande Western is selling most of its serviceable narrow-gauge rolling stock to the Sumpter Valley road of Oregon. Engine No. 7, formerly No. 04, is now newly-painted in the yards ready to ship to Baker City, and No. 02 will soon be finished. Most of the Utah Central freight cars were unfit for service and were sent to the scrap pile after the road was broad-gauged, but the best coaches were kept to be used for special stock cabooses and one for a car for the engineering department. The two best narrow-gauge engines were set-out as No. 1 and No. 13, and the balance will go to the Sumpter Valley." "The latter road, by the way, has many pieces of Utah equipment, its owners, being Utah men, seem to look to their State to supply equipment. The Garfield Beach, the Utah & Northern, and the San Pete Valley roads have supplied the Sumter Valley with cars and engines, and now the Rio Grande Western has added its quota." (Pitchard, Salt Lake Daily Tribune, 22 October 1900)
25 October 1900
"Engine 7 of the Sumpter Valley was hoisted onto a flat car yesterday in the Rio Grande Western yards and shipped to Baker City. No. 8 is soon to be ready." (Pitchard, Salt Lake Daily Tribune, 25 October 1900)
5 November 1900
"More cars of the Utah Central have been sent to the Sumpter Valley road." (Pitchard, Salt Lake Daily Tribune, 5 November 1900)
14 November 1900
"The last relic of the Utah Central narrow-gauge came down from Sugar House last night. It was a broad-gauge train loaded with narrow-gauge cars for the Sumpter Valley road. The train was pulled by set-out engine No. 5, and altogether it was a combination train worth looking at." (Pitchard, Salt Lake Daily Tribune, 14 November 1900)
16 November 1900
"Another train of narrow-gauge equipment came down from Sugar House last night to be sent to the Sumpter Valley road." (Pitchard, Salt Lake Daily Tribune, 16 November 1900)
17 November 1900
"Another train of narrow-gauge cars came down from Sugar House last night." (Pitchard, Salt Lake Daily Tribune, 17 November 1900)
10 January 1901
In an item commenting upon the extension of the Sumpter Valley line: "The Sumpter line is owned by David Eccles, C. W. Nibley and others of Utah, and they have had the foresight to greatly add to their equipment by purchasing at a reasonable figure all the rolling stock of the Sanpete Valley and Utah Central roads as soon as they were broad gauged." (Pitchard, Salt Lake Daily Tribune, 10 January 1901)
5 April 1901
"Buys Utah & Pacific" is the header of an item dated at New York on the 4th; the Oregon Short Line has exercised its option, and bought the 25% of Utah & Pacific stock held by McCune; also bought the 24% held by Eccles, Nibley and others. Eccles, in interview, said that the O.S.L. did not own any stock before this, but held options on that noted above, as well as an option on the 51% of the road's stock held in escrow, which 51% the O.S.L. has also bought, giving them 100% of the Utah & Pacific stock issue. The O.S.L. did have some $279,000 in Utah & Pacific bonds, which it took as payment for rails and equipment delivered to the U&P. Yesterday, the O.S.L. bought an additional $393,000 in U & P bonds. The stock is given as being 8,250 shares, all of which is now owned by O.S.L. A brief history of the Utah & Pacific says that the road was chartered on 19 August 1898, construction began in September of 1898 and was completed in May of 1899. (Pitchard, Salt Lake Daily Tribune, 5 April 1901)
10 April 1903
ECCLES BUYS THE LOT
Garfield Line Equipment Goes to Sumpter Valley Road.
Shipping Cars Today
Engines and All Other Equipment Sold by O. S. L.
There Are in all 191 pieces and the Lot Will Be Used on the Oregon Line.
The Sumpter Valley railway, of which Messrs. Eccles and Nibley are the leading spirits, has purchased from the Oregon Short Line all the narrow-gauge equipment of the latter company and the same will begin to move to Oregon today. This is quite a large addition to the equipment of the Sumpter Valley, as the Short Line had on hand three Mogul engines, 158 freight, outfit, water and wrecking cars, thirty passenger, baggage and excursion cars, making a total of 191 pieces. The Sumpter Valley people, however, realizing that they could get the equipment at a reasonable price and that it would all be needed when their line was extended, took the entire lot at a figure something like $40,000.
Since the road was broad-gauged and the narrow-gauge equipment laid aside the company has been deluged with offers for the cars and engines but the average prospective purchaser was of the opinion that the lot could be secured for next to nothing, and the Short Line refused all offers until the Sumpter Valley came along with quite a liberal offer and took the goods. The Moguls will find a long lost brother when they reach Baker City, as the Sumpter Valley bought all the Sanpete Valley equipment when that line was made standard. In the lot was an engine that formerly ran on the Utah Northern and later on the Garfield line before it was bought by the Sanpete road. It was in the same class as the engines which now go to Oregon. (Pitchard, Salt Lake Daily Tribune, 10 April 1903)