Ben Hom wrote

... there is Will Whittaker photo of SSRY 121 [at]

http://railroad.union.rpi.edu/rolling-stock/Box-cars/40-foot-single-sheathed/T-M-7-panel-Howe/XM-ss-7-panel-Howe-steel-Sand-Springs-Whittaker.jpg

I have a 1970's photo of SSRY 121 taken by my father. The car
was still in revenue service. A total of 4 are shown in the 1972
ORER, and I have pictures of three of them... I guess proving
the rule that oddball cars are more likely to be photographed.

Tim O.