This unit is an old AHM (Associated Hobby Manufacturers) release #26302. it displays a Union Pacific herald under the cab window, has no road number and was released in late 1982.
This unit is a reworked model of an old MRC release dating back to around 1975.
The locomotive is an RSD 15 and it was produced by Alco from February 1956 until June 1960. it was a 2400 hp locomotive and was probably an answer to the Fairbanks-Morse H-24-66 Trainmaster although it was not as heavy and did not have the same tractive effort as that unit.
the AHM model is superior to the old MRC one and, while it can not come close to the quality of the models available today, is still a good running unit.
Also, as it is very old technology the unit will be difficult to convert to DCC, if that is your intention.
I have a Santa Fe unit, however, the whole thing including the body shell is in pretty rough shape and has been since the 5 year old son of an old girlfriend, back in 1983 threw it at the living room wall for whatever reason, known only to him and defended by his mother, who did not stay my girlfriend for long after that.
Terry.