In September, 1880, the two Summit County engines appear on the Utah & Northern account, both of them appearing as an 'equipment expenditure' for the U&N, at a cost of $5,000 for the both of them.

U&N 1 (2nd) as Summit County No. 2, was built Baldwin class number 8/18D-11, had 12 x 16" cylinders, 36-inch drivers, and engine weight of 38100 pounds, and became U & N 2nd No. 1 before being renumbered in 1885 to No. 290.

Summit County Railroad No. 2 was turned over to the Utah & Northern on March 26, 1878, while the U&N was, in fact, still the Utah Northern Railroad. Eventually Summit County No. 2 became Utah & Northern 2nd No. 1, but the exact date is unknown, since U&N's first No. 1, the Grant 2-4-0, is on the property through September of 1881. It is known that Summit County No. 2 operated on the Utah & Northern for some time as SCRR No. 2, and was not officially transferred, apparently, to the U&N until September of 1880. It may be the case that the U&N's original No. 1, being after all a very light 2-4-0 with huge drivers, was out of service and 'retired' for some time prior to its actual sale in September of 1881, perhaps early enough to allow the renumbering of SCRR No. 2 to U&N 2nd No. 1 by September of 1880.

A precedent exists, on a UP-controlled narrow gauge line, for the denumbering of an old, light engine to make way for better power. On the Colorado Central Railroad, where the ancient and underpowered 0-4-0 engines lost their numbers in 1874 and 1875, two of them remaining on the line as late as 1879, identified only by names applied when un-numbered. It's easy to see a similar occurrence on the Utah & Northern in 1880.

U&N 22 as Summit County No. 1, was built Baldwin class number 12D-16, had 11 x 16" cylinders, 36" drivers, and engine weight of 35,000 pounds, and became U & N No. 22, in 1885 renumbered to No. 2, one of four engines in class DF-1.

Both engines were dropped from equipment prior to January 1, 1891, and scrapped.

U&N 45 on the Utah & Northern was an odd engine indeed, it being the old 0-4-4T Mason 'bogie' engine built in 1871, on speculation, and sold in April of 1872 to the American Fork Railroad as their (first) No. 1, and named "American Fork" on that road. In service, it soon proved too light, and was offered for sale in April 1873; the last mention of it that I have found, where I am sure that it is on the American Fork RR property, is in September of 1873. From that date, until it appears on the Utah & Northern Railway in 1883, its whereabouts, for an entire decade, is unknown.

Specifications: 11x15-inch cylinders; 34 inch drivers; 29,900 pounds; dropped from equipment in 1886. Although only 15 years old in 1886, when it was dropped from the equipment, it is presumed that the engine was scrapped at the same time.

Utah & Northern Ry. No. 45 began life as a sort of demonstrator, the first locomotive built by Mason on the single-boiler Fairlie design now so well-known as the "Mason Bogie" locomotive, built in late 1871 to early 1872 with no specific purchaser in mind, simply to demonstrate the principles involved. In April of 1872, it was sold (with an order for a twin) to the American Fork Railroad, to which it was shipped on July 1, 1872, being assigned shop number 461 at that time. It was numbered AFRR No. 1, and named "American Fork" as well. This locomotive being rather light, it was not exactly a stunning success on a railroad having grades of 296 feet per mile (nearly 6 percent), and was offered for sale before the commencement of the second season of operations on the American Fork RR. There were no immediate takers, and the locomotive was not sold until late in 1873, probably December, to the organizers of the Eureka & Palisade RR, in Nevada. After passing through the Central Pacific's shops at Carlin for what appears to have been a refurbishing and repainting, this engine appears on the Eureka & Palisade RR in early 1874 as that road's No. 1, named "Eureka." In 1875, upon the arrival of a new Baldwin 4-4-0 named 'Eureka' (which still exists), the Mason appears to have been renamed "Onward," possibly as a result of someone having seen one or another of the large number of pictures of a 'similar' engine so named, or perhaps as a result of having discovered that name under several layers of paint on the engine.

E. & P. No. 1, by whatever name, was sold in October 1879 to the then-being-built Nevada Central Ry., as its No. 2, named "Austin," which in mid-1881 is renumbered to 2nd No. 3, on account of the arrival of a new Mogul No. 2 from Baldwin; while it may have retained its name "Austin" as the new No. 3, it seems most frequently to be referred to as the "Dinkey" in this period. In December 1882, the "Dinkey" (No. 3) is transferred to the Utah & Northern, to be used 'temporarily' on that road, likely as a switcher; the freight charge of $132.93 is charged to the Utah & Northern's equipment account in December 1882, and the temporary transfer ends up as a permanent thing, and the engine is assigned No. 45 on the U&N. Renumbered in 1885 to number 296, it was vacated in May 1886, and scrapped.

Nevada Central Ry. 2nd No. 3 transferred to Utah & Northern Ry. in December 1882, to be used 'temporarily' (according to the journal entry), but which was retained, and assigned U & N No. 45. The engine was an 0-4-4T "Bogie" built by the Mason Machine Works, Taunton, Mass., construction number 461, 1 Jul 1872, having 10x15" cylinders, 33" drivers, and an engine weight of 14 tons. In 1885, this engine was renumbered to U&N No. 296, with the system roster of June 1, 1885 showing the engine as having 11x15" cylinders, 34" drivers, and engine weight of 29,900 pounds As No. 296, this engine was declared vacant in May 1886, and scrapped.