Outshopped in 1923 by Baldwin Locomotive Works, the Southern Pacific's class P-10 4-6-2s weighed 300,000 pounds and produced 36,960 pounds of tractive force. They had 73-inch drivers and 23x30-inch cylinders, and sustained 200 p.s.i. of boiler pressure. Additionally, they had 3352 square feet evaporative heating surface and 815 square feet superheater surface, with a grate area of 70 square feet. The Vanderbilt-style tender held 4000 gallons of fuel oil.
No. 2486 of the P-10 class appears here in a photo provided by William D. Volkmer, and dated November 2, 1953 at Oakland, California. No. 2486 belonged to a group equipped with a trailing truck booster, which raised the starting tractive effort to 43,660 pounds. In 1941 three of the P-10s, including this locomotive, were semi-streamlined with a skyline casing and side skirts (the latter removed before this photo was taken), giving them the appearance of the famous "Daylight" GS 4-8-4s. As so equipped, they pulled the San Joaquin Daylight between Oakland and Bakersfield.