Should'na typed without checking. The last car of Class B-50-34, car no. 110249, was constructed by SP Equipment Co. in November, 1954, with a prototype Hydra-Cushion underframe fabricated by Consolidated Western Steel from SRI drawings. This car became 650831 in 1956, and was classified as B-50-34-X at least as early as March, 1955.
And as Tony pointed out in another email in a galaxy long ago and far away, from April 26, 1956 to November 30, 1956, the car wore the number 171490!
Also according to an earlier Tony email, the 110249 was built on December 28, 1954.
Keeping track of SP freight car renumbering is fun!
Tim O'Connor <timboconnor@...> -->> NOTE EMAIL CHANGE <<-- Sterling, Massachusetts