Dave,
I can offer the following information about #306, extracted from the late George E. Pitchard's fine piece of research
A Utah Railroad Scrapbook - privately published in 1987.
Early in the 1890's, the Rio Grande Western acquired the Utah Central Railroad, by lease, that being the narrow gauge line from Salt Lake City to Park City by way of Parley's Canyon. With the road came several engines, only three of which, the 2-8-0 engines numbered 1, 2 and 3 did the RGW keep in service. The RGW numbered the engines 01, 02 and 03 by adding a zero in front of the UC number.
THe 01 carried a construction number of 14487, built on 10/1895. It had drivers of 37" and had cylinders of 16" x 20".
It was rebuilt to standard gauge in 1900 and renumbered 1. It was passed to the D&RG in April 1909 and renumbered 554. It was narrowed again in 1918 and renumbered to 306 in 1924. It was scrapped in January, 1935.
Regards,
Vic Stone