I would disagree on a 1928 photo date. Zoom in on the photo. I can get to 250% and see the small lettering pretty well.
Look to the right of the door and there is a 1916 build date.
To the left of the door we can see the WT stencil. That line reads K 11/16 NEW WT. This is the first weighing of the car when it was new. Subsequent reweigh info would not include the NEW here. This is one of the earlier Southern double sheathed 36-foot box cars. The Westerfield models reflect the 1922-26 built cars, which had a slightly larger cubic capacity.
The “S” could be an indication of a steel center sill. Note there is something like a trust plate above the “S” in Southern at the fascia.
El Paso, TX
I noticed after I sent my note that there is a trust plate above the “S”. I checked the Standard and Poor’s for Southern Equipment Trusts and there are a number of them, including for subsidiary companies like Mobile and Ohio Railroad, whose March 1, 1923 Series “L” Gold Bonds that were fully payable in March, 1936 included “400 40-ton 36-ft. boxcars”. M&O had another equipment trust from January 1, 1924 that included “1,000 40-ton boxcars”.
Southern’s equipment trust of Dec. 31, 1927, included “250 40-ton steel underframe box cars. Locomotives, passenger cars and other freight equipment were included in the equipment trusts. Perhaps, before 1924, Southern could not obtain access to equipment trusts or the banks did not want the truss rod equipment in trusts since these are a small part of their trust rod boxcar fleet.
The date of the photo is likely 1928.
south of Mike Brock