The Cache Valley RR (connecting with Frisco at Sedgwick AR) owned at least two 4-4-0 locomotives, numbered 503 and 508. 503 was built by Rogers in 1887 and 508 by Schenectady in 1891. Both were purchased second-hand by the Cache Valley. Frisco or Frisco predecessor companies would have been the most likely source... do these locomotives match any known early Frisco locomotives?
I think the Cache Valley RR was a narrow gauge road, so the Frisco was likely not the source of the locomotives. Ken McElreath
Cache Valley was narrow gauge (3'6" gauge) until early 1904, when it was standard gauged. The two 4-4-0s were purchased after it became standard gauge.