The capacity of the SP&S cars is listed as 16,000 gallons in an SP&S diagram book. One photo I has reads 16,025 GALS. on the tank end.
Built September 1949 by GATC. A.S.F. A-3-ride control. 6" outlet in bottom. heater coils. Roller bearings on 38610 and 38611 as of 1963.
Five SP&S still listed in ORER in 1995.
I dug out a photo of a Santa Fe car, and they look the same to me, except for the SP&S having a vertical brake handle shaft.