D, S. Publishing is something I'm unfamiliar with, but I have some information about Seaboard.
Seaboard Published 5 issues of Fast Fiction, skipped a month Then reprinted them in order as Stories by Famous Authors Illustrated followed by 8 new issues. In Issue 13, they printed a "Coming Next" page for no. 14 "The Red Badge of Courage." Their format was identical to Classics Illustrated and the main Classics artist, Henry C. Keifer at least 4 or 5 issues of FAI.
Gilberton (publishers of Classics Illustrated) acquired Seaboard before the 14th issue was published. Gilberton acquired not only the company name but also the 30 the 30 pages drawn for "Red Badge of Courage" which they published in the 98th issue of Classics Illustrated. The used the Seaboard name and (I assume) printing contracts as an in-house publisher creating a new title, Classics Illustrated Junior which lasted 76 Issues. I will stop here so I don't write twenty or thirty pages about CI. There are extra Classic Illustrated issues in Europe, Greece, 1 in Italy and over 100 in Brazil.