SAL 13000-series were the B-4 class cars. My information shows there were 1,000 cars delivered in two lots: 13001-13500 delivered from Pressed Steel, Baltimore in April 1929, and 13501-13999 also from Pressed Steel delivered in August. I acknowledge the series stops in the ORER at 13965.
A large number of these former B-4 cars were rebuilt to maintenance of way cars in the 1940s and 1950s. I've counted at least 19 different maintenance cars were originally B-4 box cars. Many of those cars were re-sheathed with plywood--but AFTER they were rebuilt for maintenance. Also, at least 100 cars were rebuilt into R-4 wood racks in the late 1940s.
To your question: I have run across no evidence that any B-4s were rebuilt with steel sheathing.
A small number of B-3 class cars (12000-12999) were rebuilt with steel sheet inside the trusses by 1940. Most of the B-3s were rebuilt into wood racks, stock cars, and maintenance cars. Over 1,200 of the 2,000 B-5s were rebuilt with steel sheathing in at least three different variations...but that wasn't your question of course.
I have lots of images, but nothing showing a steel-sheathed B-4.