The original S-38
The S-38 series are postwar AC-DC general coverage receivers. Several models have one side of the line cord switched to the chassis. For safety, an isolation transformer is strongly recommended. The original insulation between the chassis and metal cabinet must remain intact.
Given the low-end circuitry, these sets are surprisingly sensitive when aligned and operating properly. Many an amateur radio operator and short wave listener started out with one of these. The S-38 (no letter), S-38A, and S-38B all have similar dial faces and black cabinet color. The S-38C was the first of the series with cabinet color in gray metallic. The original S-38 (no letter) has 6 tubes with one used for the BFO. It also has a variable BFO control on the front panel and an additional red slide switch on the left side for noise limiter. The circuit is very similar to the Echophone EC-1A/B, and the S-41G/W with the exception of 4 bands rather than 3. Toward the end of the original 6 tube S-38 model run, a 5 tube version was introduced which became the "A" and the standard for the entire series, using regenerative IF for the BFO. The last of the series, S-38E (below) had a rear-panel variable BFO injection control and used seven-pin miniature tubes. All the others used octal tubes.
Years of introduction as indicated by first advertisement for the series were: S-38 (no letter) = 1946 (advertised from 1946 to 1949. Price reduced in Allied and WRL ads May and June 1949), S-38A = 1949 (earliest ad I have found is August 1949), S-38B = 1950 (earliest ad I have found is August 1950), S-38C = 1952 (Other sources indicate 1953 as year of introduction but the first ad appears in Radio-TV News in July 1952), S38-D = 1955, S-38E = 1957.
If you find earlier ad dates for any of these models, let me know.