Facts and Figures
Builder :	ALCO (American Locomotive Company)
Model : S6
Builders Number: 81301
Date Delivered: June, 1955
Original Number: 1051 (1955 to 1965) (SP class DS9)
Final Number: 1218 (System Renumbering in 1965, changed to SP class AS409-1)
Engine Model: 251B
Horsepower: 900 @ 1000rpm (turbosupercharged)
Weight : 232,780 pounds
Length : 45' 6"
Height : 15' 10"
Width : 10' 3"
Fuel Capacity: 635 Gallons

The locomotive was bought new by the Southern Pacific in 1955 and  was part of an order for 19 identical units.  Out of a total of 93 locomotives constructed by ALCO for domestic use, the Southern Pacific owned 70 which were purchased in 1955 and 1956 in 5 different groups.  They lasted on the SP system until the summer of 1980 and never received heavy modifications.

These are pages from a 1957 Southern Pacific Diesel Unit Diagram Book.   It is interesting to note that the book shows the locomotive equipped with a speedometer but there is no sign of there ever having been one installed.